,ri_n__n — 


REESE  LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Deceived  ,  190     . 

Accession  No.        82890'   Clots  h\-. 


BOILER    TESTS; 


EMBRACING  THE  RESULTS  OF  ONE  HUNDRED  AND 
THIRTY-SEVEN  EVAPORATIVE  TESTS,  MADE 
ON     SEVENTY-ONE     BOILERS,    CON- 
DUCTED BY  THE  AUTHOR. 


BY 


GEO.  H.  BARRUS,  S.  B., 

MEMBER  OF  AMERICAN  SOCIETY  OF  MECHANICAL   ENGINEERS, 
AND  BOSTON  SOCIETY  OF  CIVIL  ENGINEERS. 


BOSTON: 

PUBLISHED    BY    THE    AUTHOR. 
COWING  &   CO.,  AGENTS, 

70   KILBY    STREET. 
I89S. 


Copyright,  1891,  by 

GEO.     H.    BARRUS. 


F.  H.   GILS"N    COMPANY, 

PRINTERS    AND    BOOKBINDERS, 

BOSTON,    MASS. 


PREFACE. 


Tins  book  relates  to  a  large  number  of  evaporative  tests, 
which  were  conducted  personally  by  the  author.  The  sub- 
stance of  Parts  I  and  II,  which  form  the  body  of  the  work, 
was  originally  prepared  at  the  request  of  the  New  England 
Cotton  Manufacturers'  Association,  and  embodied  in  a  paper, 
which  was  read  to  that  Society.  A  few  copies  of  the  paper 
were  reprinted  from  the  Transactions  of  the  Association,  and 
furnished  to  parties  interested  in  the  subject.  The  supply  of 
these  was  quickly  exhausted.  The  favor  with  which  the  paper 
was  received,  not  only  by  members  of  the  Association,  but  also 
by  those  who  have  been  supplied  with  the  reprints,  led  to  its 
publication  in  the  present  form.  In  the  revised  work  the  ar- 
rangement and  numbering  of  the  various  boilers  have  be^n 
changed,  and  cuts  have  been  introduced  to  show  the  general 
features  of  the  boilers  tested.  An  index  has  also  been  added. 
These  changes  supply  what  was  lacking  in  the  paper  as  first 
prepared,  and  give  to  the  work  that  degree  of  completeness 
which  is  desired  in  a  book  of  reference. 

The  author  has  made,  in  later  tests,  investigations  of  the 
heating  power  of  various  fuels,-  determining  the  heat  of  com- 
bustion, for  this  purpose,  by  the  use  of  a  coal  calorimeter. 
It  has  been  thought  desirable,  in  view  of  the  bearing  which 
these  investigations  have  upon  the  general  subject  of  boiler 
tests  and  the  combustion  of  fuel,  to  give  a  brief  account  of 
the  work  in  connection  with  the  tests  under  consideration,  and 
this  has  been  done  in  the  Appendix.  There  is  also  presented 

(3) 


82890 


4  PREFACE. 

iii  the  Appendix  a  portion  of  the  author's  paper  on  "  A  Uni- 
versal Steam  Calorimeter,  "  which  is  added  partly  on  account 
of  its  bearing  on  the  subject,  and  partly  because  it  has,  in  the 
author's  later  tests,  taken  the  place  of  the  Superheating  Calo- 
rimeter, referred  to  in  Part  I. 

The  book  is  offered  to  the  public  in  the  belief  that  it  is 
of  considerable  interest  and  value  to  steam  engineers,  manu- 
facturers, and  any  persons  who  are  concerned,  either  directly  or 
indirectly  in  the  burning  of  coal  and  the  economical  genera- 
tion of  steam. 

GEO.  H.  BAUKUS. 

95  MILK  ST.,  BOSTON, 
May,  1891. 


CONTENTS. 


PART  I. 

INTRODUCTION,      .         . 9 

METHODS  EMPLOYED  IN  CONDUCTING  THE  TESTS,       .         .13 
EXPLANATION  OF  THE  TABLES  OF  PART  SECOND.   .         .19 
DISCUSSION  OF  RESULTS,         .         .         .         .         .         .21 

COMPARISON    OF    BOILERS    WHICH    PRODUCE    SATURATED 

STEAM  WITH  THOSE  PRODUCING  SUPERHEATED  STEAM,     22 
GENERAL  CONDITIONS  WHICH  SECURE  ECONOMY,        .         .28 
COMPARISON  OF  DIFFERENT  KINDS  OF  BOILERS,         .         .36 
COMPARISON  OF  DIFFERENT  KINDS  OF  FUEL,    .         .         .43 
MISCELLANEOUS  DISCUSSION,  .         .         .          .         .         .51 

FLUE  HEATERS, 56 

PART    11. 

TESTS  OF  HORIZONTAL  TUBULAR  BOILERS.         .  .  .67 

TESTS  OF  HORIZONTAL  DOUBLE-DECK  BOILERS,  ,  .  159 

TESTS  OF  PLAIN  CYLINDER  BOILERS,         .         .  ,  .174 

TESTS  OF  VERTICAL  TUBULAR  BOILERS,  .         0  .  .183 

TESTS  OF  CAST  IRON  SECTIONAL  BOILERS,     .  .  .211 

TESTS  OF  WATER-TUBE  BOILERS,    .         .         .  .  .217 

SUMMARY  OF  TESTS 234 

APPENDIX. 

A  COAL  CALORIMETER,  .....         0         .  249 
A  UNIVERSAL  STEAM  CALORIMETER,         .  .255 


PART  I. 


BOILER  TESTS 


INTRODUCTION. 

In  the  pursuit  of  his  business  as  a  steam  engineer  the  author 
has  had  frequent  occasion  during  the  past  ten  years  to  make 
evaporative  tests  of  steam  boilers.  The  interests  which  have 
led  to  the  work  are  of  a  varied  character.  Inventors  or  build- 
ers of  new  types  of  boilers  have  been  desirous  of  learning 
what  economical  features  their  improvements  possess ,  and  they 
have  called  for  the  results  of  an  evaporative  test  as  a  means  of 
comparison  with  the  performance  of  existing  boilers  ;  01%  know- 
ing themselves  the  economy  of  the  improved  generator,  they 
wished,  for  purposes  of  trade,  to  corroborate  their  own  testi- 
mony of  its  superiority,  by  the  certificate  of  a  disinterested 
engineer.  Managers  of  factories  have  sought  advice  upon  the 
cause  of  excessive  consumption  of  coal  in  their  steam  plants. 
To  solve  this  problem  it  is  necessary  to  ascertain  the  evapora- 
tive efficiency  of  the  boilers,  so  as  to  separate  the  process  of 
generating  the  steam  from  that  of  its  use  after  generation. 
They  have  also  desired  information  upon  the  general  economy 
of  their  boilers,  and  upon  the  kind  of  fuel  which  it  would  be 
most  advantageous  to  burn,  when  all  the  questions  of  current 
price,  evaporative  efficiency  and  incidental  advantages  and  ob- 
jections are  taken  into  account — questions  which  can  be  deter- 
mined satisfactorily  only  by  means  of  an  evaporative  test. 
They  have  had  occasion,  too,  before  completing  a  settlement 
with  the  contractor  for  a  new  plant  of  boilers,  to  call  for  a  test, 
to  ascertain  whether  in  capacity  or  economy,  or  both,  the  boil- 
ers do  their  work  in  the  manner  stipulated  in  the  contract. 
They  have  also  sought  information,  which  only  an  evaporative 


10  BOILEE   TESTS. 

test  affords,  to  guide  them  in  the  selection  or  arrangement  of  a 
contemplated  new  boiler  plant,  or  in  the  renewal  of  an  old 
plant.  Capitalists  have  called  for  evaporative  tests  upon  im- 
proved forms  of  boilers,  in  which  they  have  in  view  the  invest- 
ment of  money,  that  they  may  learn  from  outside  investigation 
whether  the  inventor's  claims  are  well  founded,  or  whether  the 
improvement  is  of  sufficient  merit  to  warrant  the  investment. 
Finally,  a  large  class  of  persons,  bent  on  seeking  information, 
have  had  boilers  tested,  so  as  to  find  out  whether,  in  one  way 
or  another,  the  evaporative  efficiency  could  be  improved. 

In  every  case,  whether  the  test  has  been  made  at  the  solici- 
tation of  the  inventor,  the  mill-manager,  the  capitalist  or  the 
investigator,  there  has  always  been  one  controlling  object  in 
view,  on  the  part  of  the  author,  and  that  is,  the  determination 
of  the  true  performance  of  the  boiler,  and  the  work  has  been 
undertaken  in  every  instance  with  the  unbiased  feeling  of  a 
student,  interested  only  in  getting  at  the  facts. 

In  this  work  the  number  of  individual  tests  w^hich  have  been 
made  has  reached  a  sum  between  three  hundred  and  fifty  and 
four  hundred.  Many  of  them  have  been  made  in  the  New 
England  States.  The  boilers  have  been  situated  in  cotton  mills, 
woollen  mills,  and  other  textile  factories,  paper  mills,  machine 
shops,  lumber  mills,  rubber  works  and  public  buildings. 
They  have  embraced  plain  cylinder  boilers,  horizontal  return 
tubular  boilers,  locomotive  boilers,  vertical  tubular  boilers, 
water-tube  boilers,  sectional  boilers  and  patented  boilers  of  va- 
rious kinds.  They  have  been  set  in  brick-work,  set  without 
brick- work,  set  according  to  patented  methods  and  set  in  the 
ordinary  way.  They  have  been  fired  with  anthracite  coal  of 
various  kinds  and  sizes,  bituminous  coal  of  various  kinds,  an- 
thracite screenings,  mixtures  of  anthracite  screenings  and  bitu- 
minous coal,  petroleum  oil  and  coke. 

The  paper  is  devoted  to  an  analysis  of  many  of  these  tests. 
Of  the  number  referred  to,  those  which  are  omitted  are  either 
of  a  private  nature  or  are  devoid  of  general  interest.  They 
were  all  conducted  personally  by  the  author,  with  the  exception 
of  one  set  of  tests,  which  were  made  by  an  assistant  who  worked 
under  the  author's  direction. 


INTRODUCTION.  H 

The  tests  are  so  varied  in  object,  in  conditions,  and  in  type 
of  boiler,  that  it  has  proved  advisable  to  take  up  each  boiler 
and  the  tests  made  upon  it,  separately,  and  give,  as  briefly  as  a 
clear  presentation  of  the  subject  warrants,  the  general  features 
and  dimensions  of  the  boiler,  the  data  and  results  of  the  tests, 
and  memoranda  of  the  main  points  of  information  which  the 
tests  reveal.  Given  in  this  form,  the  reader  will  find  means 
for  studying  the  subject,  if  desired,  from  his  own  standpoint. 
The  special  object  of  the  paper  is  an  examination  of  the  tests 
as  a  whole,  and  a  classification  of  the  data  and  results,  so  as  to 
put  in  connected  shape  the  information  which  they  give  as  to 
the  conditions  which  govern  the  economical  generation  of  steam 
and  the  best  practice  in  boiler  engineering. 

The  paper  is  divided  into  two  parts  ;  Part  First  embracing  the 
analysis  of  the  tests  as  a  whole,  and  Part  Second  treating  of 
the  various  boilers,  and  the  tests  made  upon  them  individually. 

Before  entering  upon  the  proposed  examination,  the  general 
subject  of  boiler  tests  and  the  methods  which  were  employed 
in  conducting  the  tests  under  consideration  demand  attention. 

The  object  of  all  boiler  tests,  first  sought,  is  the  determina- 
tion of  the  weight  of  water  evaporated  by  a  pound  of  coal. 
The  object  ultimately  sought  varies  in  different  cases.  Some 
tests  have  in  view  the  determination  of  the  efficiency  of  the 
boiler  as  a  generator  of  steam,  when  operated  under  such  con- 
ditions of  quality  of  fuel,  kind  of  firing,  capacity  and  general 
management  as  will  give  the  best  result.  These  determine  the 
true  efficiency  of  the  generator.  Others  have  in  view  the  gen- 
eral result  produced  by  the  boiler,  however  much  it  is  affected 
by  disturbing  causes,  and  they  determine  the  economy  with 
which  the  fuel  is  burned,  whether  the  type  of  boiler,  kind  of 
fuel,  capacity,  mode  of  firing  and  management  are  favorable  or 
unfavorable. 

Owing  to  the  two  general  objects  named,  boiler  tests  might 
be  divided  to  advantage  into  two  classes.  The  first  might  be 
termed  the  engineering  text,  being  of  greatest  interest  to  the 
engineer,  who  must  know  the  true  efficiency  of  the  boiler  to 
intelligently  lay  out  his  plans.  The  second  might  be  termed 


12  BOILER  TESTS. 

the  commercial  test,  being  of  most  interest  to  the  manufacturer 
or  steam  user,  who  must  know  how  the  coal  is  used  which  he 
has  to  purchase.  In  conducting  the  engineering  test  the  boiler 
should  be  worked  with  a  standard  quality  of  fuel.  It  should 
be  clean  on  both  the  interior  and  the  exterior  surfaces.  It  should 
be  fired  by  a  skillful  fireman,  who  should  use  every  exertion  to 
obtain  the  highest  efficiency  from  the  fuel.  It  should  be  worked 
at  such  a  capacity  as  will  secure  the  most  favorable  result.  The 
boiler  should  be  worked  long  enough  in  preparation  for  the  en- 
gineering test  to  heat  itself  and  the  material  in  which  it  is 
encased  to  its  normal  working  degree.  The  fire  should  then 
be  burned  down  to  a  low  point  and  thoroughly  cleaned,  a  thick- 
ness of  2  or  3  inches  of  clean  burning  fuel  being  retained  for  a 
foundation  upon  which  the  fire  of  the  test  is  to  be  started. 
With  this  thin  fire,  the  thickness  of  which  is  estimated  as  a 
basis  for  commencement,  the  test  is  begun.  The  boiler  is  then 
operated  in  the  manner  determined  upon,  for  at  least  24  hours, 
and  the  quality  of  coal  burned  and  water  evaporated  is  meas- 
ured. At  the  close  of  the  test'  the  fire  is  again  burned  down 
and  cleaned,  and  this  is  done  in  such  a  manner  that  the  condi- 
tion and  thickness  of  the  bed  of  coal  on  the  grate,  as  nearly  as 
.can  be  estimated,  is  the  same  as  it  was  at  the  commencement 
of  the  test.  For  the  commercial  test  the  boiler  should  be  oper- 
ated in  the  manner  customarily  followed,  and  the  measurement 
of  coal  and  water  taken  a  sufficient  number  of  days  to  give  an 
average  indication  of  the  performance.  In  factory  work  a  test 
of  one  week's  duration  is  of  suitable  length.  No  change  should 
be  made  in  the  daily  hours  of  running,  the  mode  of  firing,  the 
manner  of  treating  the  fires  at  night,  nor  in  the  general  opera- 
tion of  the  plant,  the  object  being  to  include  all  these  questions 
in  the  determination  of  the  main  point  at  issue. 

If  all  tests  could  be  made  in  accordance  with  these  plans 
nothing  would  be  left  to  be  desired.  The  relative  efficiency  of 
different  generators  would  be  known  at  once.  The  manufao- 

o 

turer  would  have  no  complaint  to  make  because  the  results  of 
the  test  do  not  correspond  to  those  obtained  underworking 
conditions.  Unfortunately,  no  such  uniformity  of  method  can 


METHODS   OF  CONDUCTING   THE   TESTS.  13 

be  established,  on  account  of  the  practicable  objections  and  ex- 
pense involved  in  carrying  on  tests  of  this  kind.  The  24-hour 
continuous  engineering  test  is  usually  out  of  the  question  in  a 
mill  which  uses  steam  only  10  or  12  hours  a  day.  The  six- 
days'  commercial  test  is  not  to  be  thought  of  by  the  manager 
of  a  mill,  who  counts  the  expense  for  experts'  services.  The 
ordinary  calls  for  evaporative  tests  are  for  those  which  can  be 
made  in  one  or  two  Avorking  days,  under  conditions  as  near  as 
possible  to  the  existing  ones  in  the  locality  where  the  boiler  is 
placed.  These  must  answer,  in  ordinary  practice,  for  the  pur- 
poses of  both  the  engineering  and  the  commercial  tests  in  the 
scheme  outlined  above. 

METHODS    OF    CONDUCTING    THE    TESTS. 

Nearly  all  of  the  tests  referred  to  in  this  paper  are  of  the 
last  named  class.  They  were  made,  as  a  rule,  in  factories 
working  10  or  12  hours  per  day,  where  the  fires  are  banked  at 
night,  and  where  an  interval  of  about  an  hour  occurs  at  noon 
time,  when  the  production  of  steam  nearly  ceases.  The  boilers 
were  generally  cleaned,  as  far  as  the  outside  fire  surfaces  were 
concerned,  by  the  use  of  the  tube  scraper  or  steam  jet  cleaner, 
preparatory  to  each  test.  The  inside  surfaces  were  not  cleaned 
and  generally  were  not  examined.  The  mode  of  firing  was  not 
always  the  best,  but  it  was  always  good  ;  that  is  to  say,  the  fires 
were,  as  a  rule,  free  from  "  holes  "  or  spots  where  the  live  coal 
had  died  out,  with  the  exception  of  cases  where  fine  grades  of 
anthracite  coal,  such  as  chestnut  No.  2  and  pea,  were  used,  in 
which  there  is  frequently  a  tendency  to  this  state  of  things,  and 
the  fires  were  kept  at  a  thickness  of  not  less  than  five  or  six 
inches.  When  bituminous  coal  was  burned,  it  was  usually 
fired  on  the  "spreading"  system,  and  the  bed  of  coal  was 
broken  up  and  kept  level  when  required  by  the  use  of  the 
slicing  and  stoking  bar. 

The  method  of  conducting  most  of  the  tests  given  in  the 
paper  is  as  follows  :  Preparatory  to  the  beginning  of  the  test, 
on  the  night  before  its  commencement,  the  fires  are  burned  out 
at  the  close  of  the  day's  work.  The  furnace  and  ash-pit  doors 


14  BOILER    TESTS. 

and  the  dampers  are  closed  during  the  night,  and,  in  case  only 
one  or  two  boilers  of  a  plant  are  tested,  the  stop  valves  are 
also  closed,  shutting  the  steam  into  the  boiler.  At  some  con- 
venient time  during  the  night  the  furnace  and  ash-pits  are 
cleaned.  At  five  o'clock  in  the  morning,  or  at  a  sufficiently 
early  hour  to  get  up  steam  for  the  day's  work,  the  new  fire  of 
the  test  is  started  with  enough  pine  wood  to  cover  the  grates, 
and  coal  is  fired  at  once,  and  the  boiler  brought  to  normal 
action.  Oftentimes  the  fire  is  in  working  condition  before  the 
steam  can  be  disposed  of,  and  a  pause  ensues  until  the  usual 
work  of  the  mill  begins,  during  which  time  the  fire  is  covered 
with  new  coal,  and  the  draught  choked  by  shutting  the  damper 
and  opening  the  fire  doors.  During  the  noon  hour,  when  the 
works  are  stopped,  the  fire  is  cleaned  (if  needed)  and  covered 
with  new  coal,  and  the  draught  checked  in  like  manner.  As 
the  hour  for  stopping  draws  near,  the  fires  are  carefully  burned 
down,  so  that  at  the  close  of  the  day's  work  they  are  nearly  out. 
As  soon  as  they  are  finally  extinguished,  the  contents  of  fur- 
naces and  ash-pits  are  removed  and  the  doors  and  clampers 
closed  for  the  night,  and  in  the  cases  noted  the  stop  valves  are 
shut.  When  the  coal  is  moist,  a  sample  is  selected  and  dried 
for  24  hours,  and  the  quantity  of  moisture  is  determined  by  a 
comparison  of  the  wet  and  dry  weights.  A  sample  is  taken  of 
the  ashes  and  unburned  fuel  removed  from  the  furnaces  and 
ash-pits  at  the  close  of  the  test,  and  sifted  through  a  screen 
having  |-inch  meshes.  The  proportion  of  unconsumed  coal 
which  fails  to  pass  through  the  screen  is  determined  and  applied 
to  the  total  quantity,  and  the  whole  weight  of  unconsumed  coal 
thus  found  is  deducted  from  the  weight  of  coal  fired,  to  deter- 
mine the  net  quantity  consumed.  The  value  of  the  wood  used 
for  starting  the  fires  is  taken  to  be  equivalent  in  coal  to  jfa  of 
its  weight. 

^ 

At  the  time  of  starting  the  new  wood  fire  of  the  test,  the 
position  of  the  water  line  as  shown  in  the  gauge  glass  of  the 
boiler  is  carefully  noted,  and  the  pressure  indicated  by  the 
steam  gauge  as  well.  At  the  close  of  the  test,  it  is  intended 
that  a  sufficient  amount  of  water  shall  be  supplied,  so  that  when 


METHODS   OF  CONDUCTING    THE   TESTS.  15 

the  time  arrives  on  the  next  morning,  corresponding  to  the  time 
when  the  test  was  started,  the  position  of  the  water  line  and  the 
indication  of  the  steam  gauge  shall  be  the  same  as  at  the  begin- 
ning. The  last  observation  of  the  test  is  thus  made  24  hours 
after  the  time  of  the  first  observation,  when  the  condition  of  the 
boiler  is  presumably  the  same.  If  the  water  line  occupies  a 
different  position,  a  suitable  correction  is  applied  to  the  weight 
of  water  measured,  which  is  determined  by  computing  the  quan- 
tity from  the  volume  which  it  occupies,  calculated  from  the 
known  dimensions  of  the  boiler.  If  there  is  a  difference 
of  pressure,  no  account  is  taken  of  it,  unless  the  difference 
is  large  ;  in  which  case,  the  quantity  of  evaporation  is  computed 
which  would  take  place  if  the  stop  valve  were  opened  and  a 
sufficient  amount  of  steam  let  off  to  reduce  the  pressure  from  the 
higher  to  the  lower  point.  In  conducting  a  test  according  to 
this  method,  the  small  quantity  of  evaporation  which  takes  place 
during  the  night,  produced  by  heat  stored  in  the  boiler  at  the 
end  of  the  day's  run,  is  included  in  the  total  evaporation  of  the 
test. 

During  the  progress  of  the  test  the  feed-water  is  weighed 
previous  to  its  supply  either  to  the  pump  or  injector  which 
feeds  it.  The  weighing  apparatus  consists  of  two  tanks,  one  of 
which  rests  on  a  platform  scale,  which  is  supported  by  staging 
raised  above  the  level  of  the  other.  The  water  is  first  drawn 
into  the  upper  tank.  Here  it  is  weighed  and  then  emptied  into 
the  lower  tank.  Thence  it  passes  into  the  suction  pipe  of  the 
pump  or  injector,  which  is  temporarily  changed  from  its  usual 
connection  for  the  purpose. 

All  pipes  connected  with  the  feeding  apparatus,  except  those 
concerned  in  the  work  of  the  test,  are  disconnected  ;  and  if  this 
cannot  be  done ,  the  tightness  of  valves  which  must  be  depended 
upon  is  first  assured.  If  the  blow-off  valve  leaks,  it  is  plugged. 

In  cases  where  an  injector  is  used,  and  where  there  is  no 
heater  connected  with  the  boiler,  the  temperature  of  the  water 
is  taken  at  its  entrance  to  the  lower  tank.  If  a  heater  is  used, 
the  temperature  is  taken  at  its  entrance  to  the  boiler,  a  ther- 
mometer being  set  in  the  feed  pipe  for  this  purpose.  If  both 


16 


BOILEE   TESTS. 


injector  and  heater  are  used,  the  temperature  is  taken  at  the 
tank  and  at  the  entrance  to  the  heater,  as  well  as  at  the  entrance 
to  the  boiler.  To  avoid  breakage,  the  thermometer  is  placed 
in  a  cup  filled  with  oil,  which  is  set  in  the  pipe. 

The  temperature  of  the  escaping  gases  is  determined  in  a  few 
cases  by  means  of  a  pyrometer,  the  stem  of  which  is  wholly 
exposed  to  the  gases  in  the  centre  of  the  flue .  In  general ,  the 
temperature  is  obtained  by  means  of  a  high  grade  thermometer 
set  in  an  oil  pot  filled  with  cylinder  oil,  which  is  lowered  into 
the  centre  of  the  flue.  The  pot  is  withdrawn  when  the  ther- 
mometer is  read.  When  a  pyrometer  is  used,  it  is  verified  by 
comparisons  writh  a  thermometer. 

The  draught  suction  is  determined  by  means  of  a  U-tube 
gauge,  of  the  form  shown  in  the  appended  cut,  connected  to 
the  flue  between  the  damper  and  the  boiler.  The  tube,  which 
is  made  of  glass,  is  provided  with  enlarged 
chambers  at  the  top,  arranged  so  as  to 
give  a  magnified  indication  of  the  vacuum 
produced  by  the  draught.  The  instru- 
ment is  filled  with  two  liquids  of  different 
color,  one  liquid  occupying  the  whole  of 
one  side  of  the  instrument,  and  that  part 
of  the  other  side  to  near  the  top  of  the  U- 
tube  ;  and  the  other  liquid  occupying  the 
remaining  space  in  the  U-tube  and  the 
opposite  chamber.  When  connection  is 
made  to  the  flue  (the  proper  side  being 
connected)  the  line  of  division  between 
the  two  liquids,  which,  owing  to  the  dif- 
ferences of  color  and  character,  is  clearly 
defined,  moves  downward  in  the  tube  and 
shows  by  the  distance  traversed  the  mag- 
nified amount  of  vacuum  which  is  acting. 
The  amount  by  which  the  true  indication 
is  multiplied  depends  upon  the  relation 
which  exists  between  the  diameter  of  the  two  chambers  and 
that  of  the  two  legs  of  the  tube.  An  instrument  which  multi- 


METHODS   OF  CONDUCTING  THE  TESTS.  17 

plies  eight  times,  which  is  a  sufficient  increase,  gives  a  move- 
ment of  4  inches  for  an  actual  draught  of  half  an  inch  ;  that  is, 
for  a  draught  corresponding  to  the  pressure  of  a  column  of 
water  half  an  inch  high. 

The  quality  of  the  steam,  in  the  case  of  boilers  giving  super- 
heated steam,  is  determined  by  taking  its  temperature.  A 
thermometer  is  inserted  for  this  purpose  in  an  oil  cup,  which  is 
screwed  into  the  main  discharge  pipe.  The  quantity  of  super- 
heat is  the  number  of  degrees  which  the  indicated  temperature 
is  in  excess  of  the  normal  temperature.  The  normal  tempera- 
ture is  that  indicated  by  the  thermometer  when  the  boiler  is 
under  steam  of  the  average  pressure,  at  a  time  when  the  pro- 
duction has  ceased,  that  is,  when  the  steam  is  in  a  saturated 
condition . 

In  the  case  of  boilers  which  do  not  superheat  the  steam,  the 
quality  is  determined  by  the  use  of  a  calorimeter.  The  form 
of  calorimeter  employed  is  sometimes  the  barrel  calorimeter, 
but  preferably  the  continuous  superheating  calorimeter,  devised 
by  the  author.  The  barrel  calorimeter  consists  of  a  common 
oil  barrel,  fitted  with  an  outlet  valve,  together  with  delicate 
scales  and  a  finely  graduated  thermometer.  A  series  of  tests 
is  made,  one  following  after  the  other  as  rapidly  as  possible 
and  the  results  are  averaged.  The  barrel  is  first  filled  with 
water  to  the  desired  point  and  the  water  heated  in  preparation 
for  the  tests.  This  water  is  let  out  and  thrown  away.  The 
barrel  is  then  filled  again  and  the  average  temperature  of  the 
incoming  water  is  taken,  read  to  tenths  of  a  degree,  and  the 
weight  of  water  drawn  in  is  carefully  determined.  After  blow- 
ing out  the  condensed  water  from  the  pipe  which  is  provided 
for  supplying  the  calorimeter,  a  movable  piece  of  pipe  which 
conducts  the  steam  into  the  water  is  attached,  and  the  valve  is 
opened  for  the  formal  conduct  of  the  test.  The  water  is 
heated  to  about  110  degrees.  Then  the  valve  is  shut,  the 
movable  pipe  unscrewed,  the  water  stirred  and  the  temperature 
carefully  observed.  The  weight  is  taken,  and  the  quantity  of 
steam  condensed  is  found  by  subtracting  the  previous  weight. 
Each  test  of  the  series  is  conducted  in  the  same  manner,  except 


18 


BOILER    TESTS. 


that  the  preliminary  heating  is  required  for  none  but  the  first 
test.  To  compute  the  percentage  of  moisture,  the  weight  of 
cold  water  drawn  in  is  multiplied  by  the  number  of  degrees 
difference  between  the  two  temperatures  observed,  and  the 
product  is  divided  by  the  weight  of  condensed  steam.  To  the 

THE    SUPERHEATING    CALORIMETER. 


quotient  is  added  the  temperature  of  the  heated  water,  and  the 
sum  thus  found  is  subtracted  from  the  total  heat  of  saturated 
steam  of  the  observed  pressure  (reckoned  from  zero).  The 
remainder,  divided  by  the  latent  heat  of  the  same  steam,  gives 
the  proportion  of  moisture. 


METHODS   OF  CONDUCTING    THE   TESTS.  19 

The  superheating  calorimeter,  which  is  shown  in  the  ap- 
pended cut,  works  on  a  different  principle,,  requiring  no  water 
and  no  weighing.  It  consists  of  a  heater,  through  which  the 
steam  to  be  tested  is  passed,  and  in  which  the  moisture  con- 
tained is  evaporated.  This  apparatus  determines  the  quantity 
of  moisture,  by  first  measuring  the  quantity  of  heat  expended 
in  evaporating  it,  and  this  is  readily  done  by  supplying  the 
heater  with  steam  previously  superheated  and  observing  the 
fall  of  temperature  which  the  steam  suffers  in  passing  through 
the  heater.  The  principal  data  required  are  the  temperatures 
given  by  three  thermometers,  which  do  not.  need  to  be  of  deli- 
cate construction,  nor  to  be  read  with  extreme  care.  The  quan- 
tity of  moisture  is  readily  determined  to  a  small  fraction  of  one 
per  cent.,  since  a  fall  of  some  18  degrees  in  the  temperature 
of  the  supply  of  steam  to  the  heater  is  required  for  one  per 
cent,  of  moisture. 

The  steam  which  is  supplied  to  the  calorimeter,  whichever 
form  is  employed,  is  taken  from  the  main  discharge  pipe  of  the 
boiler  by  means  of  a  well  covered  half-inch  pipe.  A  long 
thread  is  cut  upon  the  pipe,  and  it  is  screwed  into  the 
main  so  as  to  extend  across  the  whole  diameter  of  the  pipe, 
and  the  enclosed  portion  is  perforated.  In  this  manner  the 
points  of  supply  are  distributed  and  a  sample  of  the  steam  is 
obtained. 

EXPLANATION   OF   THE    TABLES    OF   PART    SECOND. 

Referring  now  to  the  various  tables  of  results  given,  some 
explanation  is  needed  as  to  the  meaning  of  the  lines  and  the 
method  of  computation  employed. 

When  the  "  manner  of  start  and  stop  and  kind  of  run  "  is 
stated  to  be  or  dinar  y,  reference  is  made  to  the  method  just  de- 
scribed, the  tests  beginning  early  in  the  morning,  after  the 
boiler  had  stood  with  no  fire  and  with  closed  dampers  during 
the  preceding  night,  and  with  no  preliminary  heating ;  there 
being  an  interval  at  noon-time  when  the  production  of  steam 
nearly  ceased,  and  the  night  evaporation  being  included  in  the 
total.  When  «  manner  of  start  and  stop  and  kind  of  run  "  is 


I  UNIVERSITY 
XlSALIFCR^ 


20  BOILER    TESTS. 

ordinary  with  preliminary  heating,  the  method  is  the  same, 
with  the  exception  that  the  night  evaporation  is  not  included 
in  the  total,  and  the  boiler  is  heated  for  a  time  preparatory  to 
the  beginning  of  the  test.  This  is  true  also  when  the  start  and 
stop  is  made  with  a  thin  fire.  When  the  "  kind  of  run  "  is 
stated  to  be  continuous,  there  is  no  interval  in  the  production 
of  steam  at  noon-time ;  and  when  it  is  spoken  of  as  a  factory 
run,  reference  is  made  to  the  case  where  the  usual  noon-day 
pause  occurs. 

The  "  duration "  of  the  test  is  the  time  required  to  evaporate 
the  total  quantity  of  water,  assuming  the  rate  of  evaporation 
which  occurs  when  the  boiler  is  doing  its  normal  work.  It  is 
the  quotient  obtained  by  dividing  the  total  evaporation  by  the 
weight  of  water  evaporated  per  hour. 

The  quantity  of  "  ash  "  is  the  refuse  of  the  furnace  and  ash- 
pits left  after  deducting  the  unconsumed  coal  which  fails  to 
pass  through  a  |-inch  screen,  and  the  percentage  is  found  by 
dividing  this  by  the  weight  of  dry  coal  consumed,  and  multi- 
plying the  decimal  fraction  thus  found  by  100. 

The  quantity  of  "  coal  consumed  per  hour"  is  found  by 
dividing  the  total  quantity  by  the  number  of  hours  determined 
upon  for  the  duration  of  the  test. 

The  quantity  of  "  water  evaporated  per  hour  "  is  found  by 
taking  the  weight  evaporated  during  those  portions  of  the  test 
when  the  boiler  is  doing  its  normal  work,  say,  in  the  case  of  a 
factory  working  10  hours  per  day,  from  7.15  to  11.45  A.  M., 
and  from  1.15  to  5.45  P.  M.,  and  dividing  this  quantity  by  the 
number  of  hours  covered  by  those  periods. 

The  "  horse-power"  is  determined  by  first  computing  the 
equivalent  evaporation  per  hour,  supposing  the  feed- water  is 
supplied  at  100  degrees  and  evaporated  at  70  pounds  pressure, 
and  then  dividing  this  quantity  by  30.  This  is  the  horse-power 
basis  of  rating  established  by  the  Committee  on  Boiler  Trials, 
appointed  by  the  American  Society  of  Mechanical  Engineers. 
The  equivalent  evaporation  is  found  by  multiplying  the  actual 
hourly  rate  by  the  total  heat  of  the  steam,  reckoned  from  the 
temperature  of  the  feed-water,  and  dividing  the  product  by 


EXPLANATION  OF  TABLES.  21 

1,110,  which  is  the  total  heat  of  steam  of  70  pounds  pressure, 
reckoned  from  100  degrees. 

The  observations  of  the  boiler  pressure,  the  various  tempera- 
tures, and  the  draught  suction  are  made  every  half  hour 
while  the  boiler  is  doing  normal  work,  and  the  results  are 
averaged. 

The  water  evaporated  "  per  pound  of  coal  from  and  at  212 
degrees"  is  computed  by  multiplying  the  quantity  evaporated 
per  pound  of  coal  by  the  total  heat  of  the  steam,  reckoned 
from  the  temperature  of  the  feed-water,  and  dividing  the 
product  by  966. 

The  water  evaporated  "  per  pound  of  combustible  from  and 
at  212  degrees"  is  computed  by  dividing  the  "  water  per  pound 
of  coal  from  and  at  212  degrees,"  by  the  percentage  of  com- 
bustible in  the  coal ;  that  is,  by  100,  less  the  percentage  of  ash, 
and  multiplying  the  result  by  100. 

In  the  tables  of  dimensions,  the  area  of  heating  surface  given 
is  that  exposed  to  the  fire  and  products  of  combustion,  and  not 
that  exposed  to  the  water  or  steam. 

No  attempt  has  been  made  in  these  tests  to  determine,  by 
chemical  analysis,  the  constituent  elements  in  the  composition 
of  either  the  coal  or  the  escaping  gases. 

The  evaporative  results  expressed  in  pounds  of  water  evap- 
orated per  pound  of  coal,  include  no  allowance  for  superheat- 
ing in  cases  where  superheating  exists,  and  are  not  corrected 
for  moisture  when  the  steam  is  found  to  be  wret.  The  quanti- 
ties given  as  "  water  evaporated  "  are  feed-water  supplied  and, 
presumably,  evaporated. 

DISCUSSION   OF   RESULTS. 

Having  now  considered  in  a  brief  manner  the  general  sub- 
ject of  boiler  tests,  and  pointed  out  the  method  of  conducting 
the  particular  tests  under  notice,  we  may  pass  to  the  chief 
object  of  the  paper;  viz.,  a  review  of  the  various  results,  and 
a  consideration  of  the  general  subject  of  economy  in  the  gen- 
eration of  steam,  as  revealed  by  the  tests. 


22  BOILER    TESTS. 

1.      COMPARISON      OF     BOILERS       WHICH     PRODUCE      SATURATED 
STEAM    WITH    THOSE    PRODUCING  SUPERHEATED    STEAM. 

The  boilers  may  be  divided  into  two  general  classes,  accord- 
ing as  they  furnish  saturated  steam  or  superheated  steam. 
The  first  class  are,  as  a  rule,  of  the  horizontal  tubular  type, 
and  the  second  class  of  the  vertical  type.  In  most  of  the 
boilers  which  superheat,  that  is,  vertical  boilers,  the  superheat 
is  obtained  by  sacrificing  the  water-heating  surface,  and  pro- 
viding a  large  area  of  steam-heating  surface.  In  the  horizontal 
tubular  boiler,  the  proportion  of  heating  surface  to  grate  sur- 
face is  generally  33  or  more  to  1,  and  this  is  almost  wholly 
water  surface.  In  many  of  the  vertical  boilers,  the  proportion 
of  water  surface  to  grate  is  only  20  to  1,  that  of  steam  surface 
to  grate  about  10  to  1,  making  a  total  of  30  to  1,  and  this  total 
surface  is  less  than  that  given  for  the  horizontal  boiler.  Con- 
sidering that  the  economic  performance  of  the  boiler  is  affected 
by  the  proportion  which  exists  between  the  heating  surface  and 
grate  surface,  as  is  shown  in  a  later  part  of  the  paper,  these 
boilers  are  handicapped  at  the  outset  by  a  deficiency  of  surface, 
even  though  the  steam-heating  surface  is  considered  equally 
as  effective  as  the  water-heating  surface.  Let  us  make  a  com- 
parison between  the  two  types  of  boilers,  however,  taking  the 
proportions  which  exist.  Although  the  evaporation  per  pound 
of  coal  is  less  in  the  superheating  boiler  than  in  the  boiler 
which  does  not  superheat,  it  does  not  follow  that  the  actual 
efficiency  of  one  is  different  from  that  of  the  other.  Super- 
heated steam  is  of  greater  value  than  saturated  steam,  according 
as  it  is  more  or  less  superheated.  The  reason  for  this  is,  first, 
that  superheated  steam  contains  the  greater  amount  of  heat ; 
and,  second,  that  heat  expended  in  superheating  steam  secures 
a  greater  return,  in  cases  at  least  where  it  is  used  for  power, 
than  the  original  heat  expended  in  evaporating  water.  If,  for 
example,  steam  is  superheated  100  degrees,  the  added  heat 
which  it  contains  is  48  thermal  units  per  pound,  or  4.8  per 
cent,  of  the  heat  required  to  convert  a  pound  of  water,  supplied 
at  212  degrees,  into  steam  of  80  pounds  pressure.  In  other 


SATURATED  AND   SUPERHEATED   STEAM.  23 

words,  if  the  boiler  evaporates  with  one  pound  of  coal  10 
pounds  of  water  supplied  at  212  degrees  into  steam  of  80 
pounds  pressure,  and  superheats  that  steam  100  degreees,  the 
excess  of  heat  due  to  its  superheat  corresponds  to  an  additional 
evaporation  of  0.48  pounds  of  water.  When  superheated 
steam  is  used  for  motive  power,  the  equivalent  value  of  the 
added  heat  is  more  than  the  quantity  named.  Many  tests  have 
been  made  which  show  that  this  is  true.  Comparative  tests  by 
the  author  show  that  for  every  ten  degrees  of  superheating,  the 
amount  of  steam  consumed  by  an  engine  is  reduced  from  1  to 
1.5  per  cent.  If,  to  be  on  the  safe  side,  we  take  a  saving 
of  1  per  cent,  of  steam  for  10  degrees  of  superheating  as  the 
proper  allowance,  and  assume  that  common  steam  contains  1 
per  cent,  of  moisture,  which,  in  round  numbers  corresponds  to 
20  degrees  of  superheat,  then  the  equivalent  evaporation  cor- 
responding to  the  effect  of  100  degrees  of  superheating,  in  the 
example  cited,  is  1.2  Ibs.  of  water  per  pound  of  coal. 

In  order  that  the  superheating  boilers  may  have  the  benefit 
of  every  advantage  to  which  they  may  be  entitled,  let  us  make 
the  comparison  on  the  supposition  that  the  steam  is  used  for 
motive  power,  and  that,  as  just  noted,  10  degrees  of  super- 
heating is  equivalent  in  value  to  1  per  cent,  increase  in  evap- 
oration. The  tests  on  the  two  types  of  boilers  which  can  be 
fairly  compared  are  those  made  with  anthracite  egg,  or  broken, 
coal,  the  principal  results  of  which  are  given  in  Tables  No.  1 
andXo.  2. 

The  number  of  tests  referred  to  in  the  vertical  boiler  table  is 
less  than  those  of  the  horizontal  table,  but  they  may  be  taken 
as  representative  examples,  since  the  comparative  results  ob- 
tained in  several  cases  where  a  different  kind  of  fuel  was  used, 
are,  in  general  terms,  the  same. 

The  average  proportion  of  heating  surface  to  grate  surface 
for  the  horizontal  tubular  boilers  is  44.7  to  1,  while  the  total 
ratio  in  the  vertical  tubular  boilers  is  34.7  to  1.  Comparing 
the  water-heating  surface  in  the  two  cases,  that  in  the  vertical 
boilers  is  about  one-half  of  that  in  the  horizontal  boilers.  The 
average  percentage  of  ash  in  the  two  cases  is  almost  identically 


24 


BOILEE    TESTS. 


SATURATED  AND   SUPERHEATED   STEAM. 


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26  BOILER    TESTS. 

the  same.  The  rate  of  combustion  is  slightly  larger  in  the 
case  of  the  vertical  boiler.  The  temperature  of  the  escaping 
gases  is  104.1  degrees  higher  in  the  vertical  boilers  than  in  the 
horizontal  boilers.  The  evaporation  per  pound  of  combustible 
is  15.7  per  cent,  larger  in  the  horizontal  boilers  than  in  the  ver- 
tical boilers,  and  the  latter  superheat  the  steam  68  degrees. 
Assuming  as  before  that  the  saturated  steam  contains  1  per 
cent,  of  moisture,  the  superheating  represents  a  gain  in  effi- 
ciency of  8.2  per  cent.,  and  there  is  left  for  the  net  superiority 
of  the  horizontal  boilers  7  per  cent. 

A  more  satisfactory  comparison  may  be  made  if  those  of  the 
horizontal  tubular  boilers,  which  are  called  u  double-deck," 
are  discarded,  as  also  those  in  which  the  heating  surface  is  de- 
ficient. Throwing  out  for  this  reason  Nos.  17,  22,  24,  42,  43, 
and  45,  the  average  quantities  for  the  remaining  ten  examples 
are  as  follows  :  ratio,  40  ;  ash,  12.6  per  cent. ;  rate  of  combus- 
tion, 10.6  pounds  ;  temperature  of  escaping  gases,  382  degrees  ; 
water  per  pound  of  combustible  from  and  at  212  degrees, 
10.90  pounds.  Comparing  the  vertical  boilers  now  with  this 
new  average,  we  have  a  difference  of  110  degrees  in  the  tem- 
perature of  the  gases,  and  17.2  per  cent,  in  the  evaporation 
per  pound  of  combustible.  This  makes  the  net  superiority  of 
the  horizontal  boilers  8.3  per  cent. 

The  superior  economy  thus  shown  is  evidently  due  in  the 
main  to  the  saving  produced  by  the  low  temperature  of  the 
escaping  gases.  A  difference  of  110  degrees  is  sufficient  to 
account  for  a  considerable  difference  in  the  results.  For  ex- 
ample, refer  to  the  tests  on  Boiler  No.  46,  which  give  the 
effect  produced  by  utilizing  the  heat  of  the  gases  in  warming 
the  feed-water.  Here  a  reduction  of  107  degrees  in  the  tem- 
perature of  the  gases  secured  an  increase  in  the  evaporation  per 
pound  of  coal  amounting  to  7  per  cent.  The  indication  of  tem- 
perature is  not,  however,  according  to  the  best  view  of  the 
subject,  a  full  measure  of  the  extent  of  the  loss  in  the  waste 
gases.  Owing  to  the  brick  setting  with  which  the  boilers  are 
provided,  and  the  tendency  which  hot  brick- work  has  to  be- 
come unsound  by  age,  it  is  probable  that,  in  ordinary  use,  a 


SATURATED  AND  SUPERHEATED   STEAM.  27 

large  quantity  of  unneeded  air  is  admitted  through  the  brick- 
work, not  only  into  the  furnace,  but  into  the  flue  space  as 
well,  which  on  the  one  hand  reduces  the  furnace  temperature, 
and  on  the  other  hand  lowers  the  temperature  of  the  escaping 
gases.  In  this  way  a  direct  loss  is  produced  by  cooling  the 
furnace ;  and  further,  the  loss  at  the  chimney,  measured  by  the 
temperature,  appears  to  be  less  than  it  really  is. 

It  is  clear  that,  according  to  these  tests,  the  vertical  tubular 
boiler  in  practical  use,  having  the  proportions  given,  is  less 
economical  than  the  ordinary  type  of  horizontal  return  tubular 
boiler ;  and  this  is  true  notwithstanding  the  superior  value  of 
the  superheated  steam  which  they  give,  for  which  the  most 
favorable  allowance  has  been  made. 

There  are  two  cases  of  vertical  boilers  in  the  paper,  where 
the  proportion  of  water-heating  surface  to  grate  surface  is  fully 
as  large  as  in  the  best  form  of  horizontal  boiler,  and  the 
unfavorable  influence  of  air  leakage  is  prevented  by  the  use  of 
a  fire-box.  The  boilers  referred  to  are  those  numbered  58  and 
60.  The  proportions  of  water-heating  surface  to  grate  surface 
are  respectively  35.1  and  44.5  to  1.  The  temperatures  of  the 
escaping  gases  are  respectively  423  and  427  degrees.  The 
evaporations  per  pound  of  combustible  from  and  at  2 1 2  degrees 
are  both  12.29  pounds.  Although  these  tests  were  made  using 
high  grades  of  bituminous  coal,  and  for  this  reason  cannot  be 
fairly  compared  with  those  under  consideration,  the  high  charac- 
ter of  the  two  results,  contrasted  with  those  referred  to,  brings 
out  very  clearly  the  fact  of  the  inferiority  of  that  type  of  verti- 
cal boiler  which  is  deficient  in  heating  surface  and  provided 
with  a  brick  setting. 

It  would  not  be  fair  to  conclude,  because  the  superheating 
boilers  referred  to  are  at  a  disadvantage  when  compared  with 
those  which  do  not  superheat,  that  this  result  must  always 
follow.  Were  the  loss  from  air-leakage  remedied  by  the  use 
of  a  fire-box,  there  is  good  reason  to  expect  that  the  vertical 
boiler  furnishing  superheated  steam  would  be  as  economical  as 
the  horizontal  boiler  furnishing  saturated  steam,  and  it  is  not 
improbable  that  with  suitable  arrangement  of  surface,  it  would 
in  the  long  run  take  the  first  place. 


28  BOILER   TESTS. 

No  data  are  given  on  either  type  of  vertical  boiler  to  show 
whether  a  considerable  degree  of  superheating  can  be  obtained, 
and  at  the  same  time  a  high  evaporative  efficiency.  It  is 
doubtful  if  the  practical  restrictions  which  the  construction  of 
the  boiler  imposes  will  allow  both  of  these  objects  to  be  real- 
ized at  the  same  time. 

It  may  be  of  interest,  in  passing,  to  note  the  effect  produced 
by  superheating  the  steam  in  an  independent  superheater. 
Under  the  head  of  Boiler  No.  1,  reference  is  made  to  a  test  on 
a  boiler  fitted  with  an  apparatus  for  this  purpose.  By  increas- 
ing the  quantity  of  coal  burned  17.8  per  cent.,  this  being  the 
coal  used  in  the  superheater,  a  superheating  of  228  degrees  was 
obtained.  On  the  basis  which  has  been  taken  for  computing 
the  value  of  the  superheat,  that  is,  a  gain  of  one  per  cent,  for 
every  ten  degrees  of  superheating,  this  steam  has  a  value  of 
24.8  per  cent,  over  that  of  ordinary  steam.  Here  is  a  net  gain 
of  7  per  cent,  in  favor  of  the  superheated  steam  when  used  for 
motive  power. 

2.       GENERAL    CONDITIONS    WHICH    SECURE    ECONOMY. 

Glancing  over  Table  No.  1,  it  appears  that,  in  general,  the 
highest  results  are  produced  where  the  temperature  of  the 
escaping  gases  is  the  least.  An  examination  of  this  question 
may  be  made  by  selecting  those  tests  in  which  the  temperature 
exceeds  the  average,  that  is,  375  degrees,  and  comparing  with 
those  in  which  the  temperature  is  less  than  375  degrees,  taking 
first  those  boilers  in  the  table  which  are  of  the  common  hori- 
zontal tubular  type.  It  will  be  remembered  that  all  of  these 
boilers  use  anthracite  coal  of  either  egg  or  broken  size.  The 
tests  with  high  temperature  are  given  in  Table  No.  3,  and 
those  with  low  temperature  in  Table  No.  4. 

The  average  flue  temperatures  in  the  two  series  are  444 
degrees  and  343  degrees  respectively,  and  the  difference  is  101 
degrees.  The  average  evaporations  are  10.40  pounds  and  11 .02 
pounds  respectively,  and  the  lowest  result  corresponds  to  the 
case  of  the  highest  flue  temperature.  In  these  tests  it  appears, 
therefore,  that  a  reduction  of  101  degrees  in  the  temperature  of 


GENERAL   CONDITIONS   OF  ECONOMY. 


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BOILEE    TESTS. 


the  Waste  gases  secured  an  increase  in  the  evaporation  of  6 
per  cent.  This  result  corresponds  quite  closely  to  the  effect  of 
lowering  the  temperature  of  the  gases  by  means  of  a  flue  heater 
in  the  case  already  noted,  where  a  reduction  of  107  degrees  was 
attended  by  an  increase  of  7  per  cent,  in  the  evaporation  per 
pound  of  coal. 

A  similar  comparison  may  be  made  on  horizontal  tubular 
boilers  using  Cumberland  coal.  Table  No.  5  gives  a  list  of 
these  tests. 

TABLE  No.  5. 

Common  Horizontal  Tubular  Boilers,  Cumberland  Coal. 


NUMBER  OF 
BOILER. 

Ratio  of 
Heating  Sur- 
face to  Grate. 

Percentage 
of  Ash. 

Coal  per 
hour  per 
square  foot 
of  Grate. 

Temperature 
of  Escaping 
Gases. 

Water  per  Ib. 
of  Combusti- 
ble from  and 
at  212 
degrees. 

Lbs. 

Deg. 

Lbs. 

5 

32.2  to  1 

11.1 

10.1 

435 

11  52 

9 

34.6  to 

6.6 

18.2 

453 

11.17 

12 

42.0  to 

6.6 

14.0 

381 

11.37 

15  av., 

37.0  to 

6.5 

9.3 

360 

11.43 

19 

29.4  to 

8.7 

10.9 

530 

10.60 

31 

.41.6  to 

6.6 

7.0 

431 

12.07 

32 

40.0  to 

6.5 

11.1 

408 

11.98 

35 

47.4  to 

8.3 

6.7 

340 

11.24 

36 

57.9  to  1 

8.3 

12.1 

397 

11.99 

40 

53.1  to  1 

7.5 

13.6 

413 

12.47 

Average, 

41.6  to  1 

7.7 

11.3 

415 

11.59 

Here  the  average  flue  temperature  is  415  degrees.  Nos. 
5,  9,  19  and  31  have  temperatures  exceeding  415  degrees.  The 
average  of  these  is  450  degrees,  and  the  average  evaporation  is 
11 .34  pounds.  The  remaining  boilers  have  temperatures  below 
415  degrees,  the  average  of  which  is  383  degrees,  and  these  give 
an  average  evaporation  of  11.75  pounds.  With  67  degrees  less 
temperature  of  the  escaping  gases,  the  evaporation  is  higher 
by  about  4  per  cent.  The  difference  here  is  less  marked  than 
in  the  anthracite  tests,  both  in  range  of  temperature  and  in 
economy,  but  it  is  in  the  same  direction ;  that  is,  the  highest 
evaporation  is  produced  where  the  waste  at  the  flue  is  the 
least. 


GENERAL   CONDITIONS  OF  ECONOMY. 


31 


The  wasteful  effect  of  a  high  flue  temperature  is  exhibited  by 
other  boilers  than  those  of  the  horizontal  tubular  class.  This 
source  of  waste  was  shown  to  be  the  main  cause  of  the  low 
economy  produced  in  those  vertical  boilers  which  are  deficient 
in  heating  surface.  Examples  of  the  same  effect  are  numerous 
in  the  case  of  nearly  every  type  of  boiler  treated  in  the  paper. 
The  cast-iron  sectional  boilers  Nos.  61  and  63  have  flue  tem- 
peratures of  575  degrees  and  462  degrees,  respectively,  and 
evaporate  at  the  low  rate  of  9.79  pounds  and  9.61  pounds  of 
water  from  and  at  212  degrees  per  pound  of  combustible.  The 
five  water-tube  boilers,  referred  to  below,  are  likewise  wasteful 
on  account  of  the  high  temperature  of  the  escaping  gases.  The 
temperatures  range  between  428  degrees  and  540  degrees,  and 
the  evaporations  between  9.68  pounds  and  10.36  pounds  for 
anthracite  coal,  and  between  10.79  pounds  and  10.98  pounds 
for  bituminous  coal,  all  of  which  are  low  results  for  their  re- 
spective grades  of  coal. 


NUMBER  OF  BOILER. 

Kind  of  Coal. 

Temperature  of 
Escaping  Gases. 

Water  per  Ib. 
of  combustible 
from  and  at 

212  degrees. 

, 

Deg. 

Lbs. 

66 

Anthracite,    .                 , 

540 

9.68 

68 

Cumberland,.        .        .. 

452 

10.7D 

69 

Anthracite,    .         . 

428 

10.36 

70 

Cambria  Bituminous,    . 

471 

10.93 

71 

Cumberland,  . 

523 

10.98 

The  plain  cylinder  boilers  Nos.  47,  48  and  49  have  a  flue 
temperature,  in  the  most  favorable  case,  of  567  degrees,  and  an 
evaporation  of  only  9.22  pounds  of  water  from  and  at  212  de- 
grees per  pound  of  combustible,  and  the  evaporation  is  reduced 
as  the  flue  temperature  increases.  The  Galloway  boiler  No. 
50,  under  extremely  favorable  circumstances  as  to  kind  of  fuel, 
mode  of  firing  and  general  management,  gave  an  evaporation  of 
only  11.06  pounds,  this  low  result  being  due,  evidently,  to  the 
fact  that  the  temperature  of  the  escaping  gases  was  at  the  high 
figure  of  575  degrees. 


32  BOILEE    TESTS. 

With  this  accumulation  of  examples,  no  other  conclusion  can 
be  drawn  than  that  one  of  the  vital  principles  underlying  the 
attainment  of  economy  in  the  generation  of  steam,  is  a  low  tem- 
perature of  the  escaping  gases.  What  the  temperature  should 
be  to  secure  the  best  results  is  to  some  extent  uncertain.  In 
the  examples  of  horizontal  tubular  boilers  cited,  the  best  aver- 
age results  where  anthracite  coal  is  used  are  secured  with  an 
average  temperature  of  343  degrees,  and  where  Cumberland 
coal  is  used  with  an  average  of  383  degrees.  It  will  not  be 
far  out  of  the  way  if  we  consider  375  degrees  as  a  proper  limit 
for  anthracite  coal,  and  415  degrees  for  Cumberland  coal. 
These  are  named  for  the  general  case.  Individual  boilers  may, 
in  rare  instances,  give  excellent  economy  where  the  waste  tem- 
perature exceeds  these  figures,  and  there  are  two  or  three 
examples  furnished  in  the  paper  where  this  is  true .  There  are 
so  many  instances  referred  to  where  a  boiler  secures  a  low 
grade  of  economy  with  more  than  375  degrees  in  the  flue  when 
anthracite  coal  is  used,  and  more  than  415  degrees  when  Cum- 
berland coal  is  used,  not  only  among  boilers  of  the  hori- 
zontal tubular  type,  but  among  those  of  all  other  types,  that  it 
seems  reasonable  to  lay  down  these  temperatures  for  a  limit. 

The  relation  between  the  heating  surface  and  grate  surface  is 
important,  and  the  question  arises  as  to  what  that  relation 
should  be  to  obtain  the  highest  efficiency.  Keeping  to  the 
common  horizontal  boiler,  let  us  select  from  the  anthracite  coal 
tests  the  boilers  in  which  the  ratio  is  below  40  to  1  and  above 
30  to  1,  and  compare  with  those  in  which  the  ratio  is  more 
than  40  to  1,  taking,  however,  only  those  cases  where  the  tem- 
perature of  the  gases  is  low  and  the  rate  of  combustion  is  above 
9  pounds  per  square  foot  of  grate  per  hour.  The  tests  used  are 
those  made  on  Boilers  Nos.  9, 10  and  15  for  the  small  ratios,  and 
Nos.  12,  25,  and  36  for  the  large  ratios,  and  the  averages  of 
the  two  sets  are  as  follows  : — 


Ratio  of  Heating  Sur- 
face to  Grate  Surface. 


Water  per  Ib.  of  Com- 
bustible from  and  at 
212  degrees. 


3G.4  to  1 
48.0  to  1 


Lbs. 
11.04 
11  05 


GENERAL   CONDITIONS  OF  ECONOMY.  33 

There  is  a  difference  here  of  11.6  in  the  ratio  given,  and 
practically  no  difference  in  the  character  of  the  results.  Nothing 
seems  to  be  gained  in  these  cases  by  increasing  the  surface 
above  a  ratio  of  36.4  to  1,  although  the  increase  amounts  to 
about  one-third.  Carrying  the  inquiry  farther,  and  taking  the 
so-called  double-deck  boilers,  of  which  there  are  four  instances 
given  in  Table  No.  1,  the  average  ratio  is  65.3  to  1  and  the 
average  evaporation  is  10.88  pounds.  Here  a  loss  is  produced, 
although  the  surface  is  increased  to  the  enormous  extent  of  80 
per  cent.  These  comparisons  are  made  with  different  kinds  of 
anthracite  coals  of  large  sizes,  and  with  different  arrangements 
of  boilers,  and  some  allowance  must  be  made  for  the  possible 
effect  which  variations  in  these  conditions  may  have  on  the 
results.  But  the  comparisons  are  suggestive.  The  evidence 
here  given  shows  that  a  ratio  of  36  to  1  provides  a  sufficient 
quantity  of  heating  surface  to  secure  the  full  efficiency  of  an- 
thracite coal  where  the  rate  of  combustion  is  not  more  than  12 
pounds  per  square  foot  of  grate  per  hour. 

Individual  examples  are  given,  which  furnish  evidence  as  to 
the  extent  of  surface  required  when  bituminous  coal  is  used. 
Boilers  No.  28  and  No.  29  are  cases  in  point.  Here  an  increase 
in  the  ratio  from  36.8  to  42.8  secured  a  small  improvement  in 
the  evaporation  per  pound  of  coal,  and  a  high  temperature  of 
the  escaping  gases  indicates  that  a  still  further  increase  would 
be  beneficial .  Among  the  high  results  produced  on  common  hori- 
zontal tubular  boilers  using  bituminous  coal,  the  highest  occurs 
in  Boiler  No.  40  where  the  ratio  is  53.1  to  1.  This  boiler  gave 
an  evaporation  of  12.47  pounds.  The  double-deck  boiler,  No. 42, 
furnishes  another  example  of  high  performance,  an  evaporation 
of  12. 42  pounds  having  been  obtained  with  bituminous  coal, 
and  in  this  case  the  ratio  is  65  to  1.  These  examples  indicate 
that  a  much  larger  amount  of  heating  surface  is  required  for 
obtaining  the  full  efficiency  of  bituminous  coal  than  for  boilers 
using  anthracite  coal.  There  is  sufficient  reason  for  this  re- 
quirement in  the  fact  that  bituminous  coal  is  of  a  gaseous 
nature,  and  the  heat  generated  in  its  combustion  is  spread 
through  a  larger  space.  The  temperature  of  the  escaping 


34  BOILEE    TESTS. 

gases  in'the  same  boiler  is  invariably  higher  when  bituminous 
coal  is  used  than  when  anthracite  coal  is  used,  and  this  points 
to  the  same  characteristic.  In  practice,  the  deposit  of  soot  on 
the  surfaces  when  bituminous  coal  is  used  interferes  with  the 
full  efficiency  of  the  surface,  and  an  increased  area  is  demanded 
as  an  oifset  to  the  loss  which  this  deposit  occasions.  It 
would  seem,  then,  that  if  a  ratio  of  36  to  1  is  sufficient  for 
anthracite  coal,  from  45  to  50  should  be  provided  when  bitu- 
minous coal  is  burned,  especially  in  cases  like  those  referred 
to,  where  the  rate  of  combustion  is  above  10  or  12  pounds  per 
square  foot  of  grate  per  hour. 

The  size  of  shell  in  horizontal  tubular  boilers  appears  to  have 
little  effect  on  the  economy.  The  best  of  all  the  results  with 
anthracite  coal,  which  is  11.53  pounds  of  water  from  and  at 
212  degrees  per  pound  of  combustible,  was  obtained  in  a  case 
where  the  diameter  of  the  shell  was  48  inches,  and  this  result 
is  all  that  can  be  expected  from  any  boiler,  whether  the  shell  is 
large  or  small. 

The  -number  of  tubes  controls  the  ratio  between  the  area  of 
grate  surface  and  area  of  tube  opening.  Boilers  No.  42  and  No. 
45  have  a  very  large  number  of  tubes,  and  consequently  a  small 
ratio  of  grate  to  tube  opening.  The  ratio  is  5.2  to  1.  They 
also  have  the  very  large  area  of  heating  surface  represented  by 
ratios  of  65  and  60  to  1.  Notwithstanding  the  ample  provision 
of  surface  and  other  favorable  conditions,  the  evaporation  with 
anthracite  coal  is  no  higher  than  boilers  give  which  have  surface 
of  much  less  extent,  though  of  such  character  that  the  tube- 
opening  bears  a  smaller  proportion  to  the  grate  surface.  The 
conclusion  which  is  well  warranted  by  this  fact  is  that  a  certain 
minimum  amount  of  tube  opening  is  required  for  efficient  work. 
This  conclusion  is  borne  out  by  the  result/  of  the  tests  with 
anthracite  coal  on  Boiler  No.  12,  where  the  products  of  com- 
bustion make  two  circuits  through  the  shell  and  the  ratio  of 
grate  surface  to  tube  opening  is  11 .6  to  1 .  The  ratio  of  heating 
surface  to  grate  here  is  42  to  1,  and  the  average  evaporation  per 
pound  of  combustible  from  and  at  212  degrees  is  11.16  pounds. 
The  best  results  obtained  with  anthracite  coal  in  the  common 


GENEEAL    CONDITIONS   OF  ECONOMY.  35 

horizontal  boiler  are  in  cases  where  the  ratio  is  larof&r  than  9 
to  1.  From  these  facts  the  conclusion  is  drawn  that  the  high- 
est' efficiency  with  anthracite  coal  is  obtained  when  the  tube 
opening  is  from  one-ninth  to  one-tenth  of  the  grate  surface. 

When  bituminous  coal  is  burned  the  requirements  appear  to 
be  different.  The  effect  of  a  large  tube  opening  does  not  seem 
to  make  the  extra  tubes  inefficient  when  bituminous  coal  is  used. 
The  highest  result  on  any  boiler  of  the  horizontal  tubular  class, 
fired  with  bituminous  coal,  is  obtained  where  the  tube  opening 
is  largest.  This  is  Boiler  No.  40,  which  gives  an  evaporation 
of  12.47  pounds,  and  the  ratio  of  grate  surface  to  tube  opening 
is  5.4  to  1.  The  next  highest  result  is  produced  in  Boiler  No. 
42,  already  alluded  to,  which  gives  12.42  pounds,  and  the  ratio 
is  5.2  to  1.  Another  high  result  is  produced  by  Boiler  No.  44. 
This  is  12.03  pounds,  and  the  ratio  is  4.1  to  1.  Table  No.  5 
gives  three  high  results,  averaging  12.01  pounds,  and  here  the 
average  ratio  is  7.1  to  1.  These  instances  are  sufficient  to 
exhibit  the  need  of  a  larger  area  of  tube  opening  when  bitumin- 
ous coal  is  used  than  when  anthracite  is  used,  and  this  might  be 
expected  in  view  of  the  gaseous  nature  of  the  products  of  com- 
bustion. Without  going  to  extremes,  the  ratio  evidently  most 
to  be  desired  when  bituminous  coal  is  used  is  that  which  gives 
a  tube  opening  having  an  area  of  from  one-sixth  to  one-seventh 
of  the  grate  surface. 

One  set  of  tests  is  given  which  bears  on  the  question  as  to 
the  effect  which  size  of  tubes  has  upon  the  economy.  These 
are  the  tests  made  on  Boilers  No.  28  and  No.  29,  in  one  of  which 
140  3-inch  tubes  are  used,  and  in  the  other  100  3J-inch. 
The  boiler  with  the  smaller  tubes  gave  the  best  result,  but  the 
improved  performance  was  evidently  due  to  the  increased  heat- 
ing surface,  of  which  there  was  an  addition  of  one-sixth,  rather 
than  to  any  difference  in  the  diameter  of  the  tubes.  It  might 
be  inferred  from  the  fact  that  bituminous  coal  requires  a  larger 
collective  area  of  tubes  for  best  results  than  anthracite  coal, 
that  it  may  also  require  a  larger  individual  area,  and  therefore 
larger  diameter  of  tubes.  This  inference  is  not  borne  out  by 
a  comparison  of  the  tests  on  Boilers  No.  42  and  No.  40,  one  of 


36  BOILER    TESTS. 

which  had  3-inch  tubes  and  one  3J-inch,  though  the  two  boilers 
are  of  somewhat  different  type.  A  practical  objection  to  the 
use  of  too  small  tubes  must  be  kept  in  mind  in  those  cases  where 
a  very  smoky  grade  of  bituminous  coal  is  used,  and  frequent 
opportunity  cannot  be  had  to  clean  the  tubes,  so  as  to  prevent 
a  serious  accumulation  of  soot. 

There  appears  to  be  no  reason  why  the  relations  of  heating 
surface  to  grate  surface,  found  desirable  in  the  horizontal  boiler, 
should  not  apply  with  equal  force  to  the  vertical  boiler,  and  this 
view  of  the  matter  is  justified  by  the  results  of  the  test  on 
Boiler  No.  60.  In  this  boiler  there  are  44.5  square  feet  of 
water-heating  surface  to  1  of  grate ,  and  7 . 1  square  feet  of  grate 
to  1  of  tube  area,  which  agree  practically  with  the  proportions 
named  for  the  best  work  in  horizontal  boilers  using  bituminous 
coal.  If  we  allow  the  equivalent  evaporation  for  the  effect  of 
the  18  degrees  of  superheating  in  the  same  manner  as  in  the 
tests  on  the  vertical  boilers,  considered  under  a  previous  head- 
ing, the  evaporation  into  saturated  steam  containing  one  per 
cent,  of  moisture  from  and  at  212  degrees  per  pound  of  com- 
bustible in  this  case  is  12.75  pounds. 

The  discussion  of  the  general  conditions  which  secure  economy 
applies  to  medium  rates  of  combustion  of  say  10  to  12  pounds 
per  square  foot  of  grate  per  hour,  such  as  will  secure  the  rated 
capacity  of  the  boiler  when  the  power  is  based  on  12  square 
feet  of  water-heating  surface  per  horse-power. 

3.       COMPARISON    OF   DIFFERENT   KINDS    OF   BOILERS. 

It  seems  to  the  author  that  the  general  principles  of  economy, 
to  which  attention  has  just  been  devoted,  though  deduced  mainly 
from  a  study  of  horizontal  tubular  boilers,  are  based  upon  such 
reasonable  grounds  that  they  may  be  applied  to  all  forms 
of  steam  boilers.  The  proportion  most  to  be  desired  between 
tube  opening  and  grate  surface  cannot  be  applied  to  a  boiler 
which  has  no  tubes  ;  but  the  relations  established  between  heat- 
ing surface  and  grate  surface,  and  the  best  condition  as  to  the 
temperature  of  the  escaping  gases,  are  principles  which  can  be 
applied  in  all  cases.  Before  making  a  comparison  of  the 


COMPARISON  OF  DIFFERENT  KINDS  OF  BOILERS.       37 

economy  of  different  types  of  boilers,  these  principles  should 
be  remembered,  and  the  comparison  based  on  the  performance 
of  the  boiler  when  suitable  conditions  exist  for  the  attainment 
of  the  best  result.  There  is  only  one  case  where  this  cannot  be 
done,  and  that  is  where  the  construction  of  the  boiler  forbids 
the  attainment  of  those  conditions. 

A  large  proportion  of  the  boilers  treated  of  in  the  paper 
are,  in  one  form  or  another,  of  the  horizontal  tubular  type.  The 
number  of  these  is  46.  Of  this  number,  there  are  31  of  the 
common  return  tubular  type  ;  1  is  what  may  be  termed  a  direct 
tubular  with  common  furnace  ;2  are  direct  tubular  with  detached 
furnace  ;  1  has  two  furnaces  for  alternate  firing ;  2  are  provided 
with  a  water  leg  for  the  front  of  the  furnace ;  3  have  such 
an  arrangement  of  tubes  that  there  is  a  double  passage  of  the 
products  of  combustion  through  the  boiler ;  6  are  of  the  double- 
deck  type. 

Of  the  remaining  boilers,  3  are  plain  cylinder,  10  vertical 
tubular,  3  cast-iron  sectional,  8  water-tube,  and  1  Galloway. 

The  most  favorable  results  with  the  common  horizontal  boiler 
are  those  obtained  on  No.  10  with  anthracite  coal,  andonNos. 
31,32,  and  40  with  Cumberland  coal.  The  first  is  11 .37  pounds, 
and  the  average  of  the  second  12.17  pounds.  The  conditions 
in  all  these  cases  were  favorable. 

The  direct  tubular  boiler  with  common  furnace,  No.  14, 
cannot  be  compared  with  these  on  account  of  the  different  kinds 
of  coal  used;  but  this  boiler  can  be  compared  with  No.  13, 
which  is  of  the  common  type  and  which  used  the  same  kind  of 
fuel.  In  this  comparison  it  stands  at  a  disadvantage,  but  there 
seems  to  be  a  reason  for  it  in  the  fact  of  the  unfavorable  pro- 
portion of  heating  surface  to  grate,  which  is  only  27.7  to  1. 

The  direct  tubular  boilers  with  detached  furnace,  Nos.  8  and 
36,  cannot  both  be  brought  into  the  comparison,  since  the 
former  used  a  mixture  of  screenings  and  bituminous  coal.  The 
latter,  No.  36,  which  was  tested  with  both  anthracite  and  Cum- 
berland coal, can  be  used.  The  anthracite  coal  gave  an  evap- 
oration of  11.33  pounds,  and  the  bituminous  coal  11.99  pounds. 
Both  of  these  are  nearly  as  good  results  as  the  high-grade 


38  BOILEE    TESTS. 

common  boilers  produced.  Here  the  heating  surface  bears  a 
ratio  to  grate  surface  of  57.9  to  1,  and  the  ratio  of  grate  to 
tube  opening  is  6.7  to  1.  Under  these  circumstances,  which 
are  most  favorable,  a  high  result  would  be  expected  from  any 
form  of  boiler,  and  the  detached  furnace  cannot  reasonably  lay 
claim  to  any  special  advantage. 

The  boiler  with  two  furnaces  for  alternate  firing,  No.  18,  a 
system  which  is  evidently  of  use  only  in  cases  where  bitumi- 
nous coal  .is  burned,  gave  a  result  much  below  that  of  a  com- 
mon boiler.  The  temperature  of  the  escaping  gases  was  472 
degrees,  which  is  too  high  for  the  best  economy.  But  this 
unfavorable  condition  does  not  wholly  account  for  the  deficiency, 
the  evaporation  being  10.93  pounds.  The  evidence  of  this 
single  instance  is  that  the  double  furnace  type  of  boiler  is  infe- 
rior to  the  common  type. 

The  boilers  which  have  a  water  leg  for  the  front  of  the  furnace, 
differ  so  little  from  the  common  boiler  that  neither  loss  nor 
gain,  if  either  occurred,  could  with  reason  be  attributed  to  this 
method  of  construction.  Boiler  No.  9,  which  is  fitted  in  this 
manner,  gave  an  evaporation  with  anthracite  coal  amounting  to 
1 1 .24  pounds.  This  excellent  result  is  largely  due,  no  doubt,  to 
the  new  condition  of  the  boiler  and  to  the  favorable  proportions 
which  existed. 

The  boilers  in  which  a  double  passage  of  the  products  of 
combustion  occurred  are  Nos.  4,  12,  and  38.  Only  one  needs 
to  be  considered,  viz.,  No.  12,  the  others  being  foreign  to  the 
discussion.  Here,  a  favorable  result  is  produced  with  anthracite 
coal,  the  evaporation  being  11.20  pounds  of  water  from  and 
at  212  degrees  per  pound  of  combustible,  and  here,  again, 
favorable  conditions  lent  their  aid.  The  result  obtained  with 
bituminous  coal  is  rather  low.  According  to  the  conclusions 
which  we  have  reached  as  to  the  best  proportions  of  boilers, 
the  tube  opening  is  insufficient,  being  only  a  little  more  than 
one-half  of  that  laid  down  for  bituminous  coal.  This  form  of 
boiler  is  not  well  adapted  for  securing  a  large  tube  opening, 
because  with  a  given  number  of  tubes  only  half  of  them  can 
be  employed  for  carrying  the  products  in  one  direction.  The 


COMPARISON  OF  DIFFERENT  KINDS   OF  BOILERS.        39 

desired  end  must  be  secured  by  reducing  the  length  of  the  tubes 
and  increasing  their  number,  using  a  larger  shell.  The  test 
gives  no  indication  of  the  result  which  would  follow  this  change 
of  construction. 

The  double-deck  boilers  No.  42  and  No.  45,  burning  anthracite 
coal  with  high  rates  of  combustion,  give  an  average  evaporation 
of  11.05  pounds.  Those  numbered  42  and  44,  burning  bitu- 
minous coal,  give  an  average  of  12.22  pounds.  One  is  slightly 
below  the  standard  of  the  common  tubular  boiler  and  the  other 
slightly  above  it.  Here  the  benefit  with  bituminous  coal  is 
due  undoubtedly  to  favorable  proportions. 

With  all  the  various  modifications  in  the  type  of  horizontal 
tubular  boiler  to  which  the  tests  refer,  some  of  which  it  must 
be  admitted  give  excellent  results,  there  is  no  other  conclusion 
to  be  drawn  than  that  the  form  of  horizontal  boiler,  which  with 
suitable  proportions  and  operation  can  be  depended  upon  to 
give  the  highest  evaporation,  is  the  common  horizontal  return 
tubular  boiler,  so  widely  used  in  New  England  factories. 

Passing  to  the  boilers  of  the  other  types  named,  the  first  is 
the  plain  cylinder.  Little  need  be  said  of  this  boiler,  it  is  of 
such  evident  inferiority  as  an  economical  generator  of  steam. 
The  ratio  of  heating  surface  to  grate  surface  is  in  no  case  above 
10.9  to  1.  If  36  square  feet  of  heating  surface  is  required  for 
economical  results,  nothing  can  be  expected  from  a  proportion 
of  less  than  one-third  of  this  quantity,  and  it  is  probably  out 
of  the  question  to  institute  a  re-arrangement  in  this  type  of 
boiler  which  will  secure  the  desired  end  in  any  practical  way. 

The  next  form  is  the  vertical  boiler.  This  has  already  been 
taken  up  under  the  head  of  superheating  boilers,  and  only  the 
conclusions  there  derived  require  mention.  These  are,  that  if 
suitable  attention  is  given  to  the  design  of  the  boiler,  the  ver- 
tical tubular  compares  favorably  with  the  horizontal  boiler. 
The  example  afforded  by  Boiler  No.  60,  using  Cumberland 
coal,  corroborates  this  view  in  the  most  positive  manner.  The 
result  obtained  in  this  one  case,  when  reduced  to  the  basis  of 
horizontal  boilers  giving  steam  containing  one  per  cent,  of 
moisture,  in  the  manner  pointed  out  for  superheating  boilers, 


40  BOILEll    TESTS. 

is  an  equivalent  evaporation  of  12.75  pounds  of  water  from 
and  at  212  degrees  per  pound  of  combustible.  We  have  a 
result  here  which  surpasses  any  given  in  the  paper  by  horizon- 
tal tubular  boilers.  Vertical  boiler  No.  58,  though  of  a 
different  arrangement,  gave  a  result  which,  without  allowance 
for  superheating,  is  precisely  the  same.  These  instances  are 
not  of  sufficient  number  to  establish  the  vertical  boiler  as  one 
of  superior  economy  to  the  horizontal  boiler,  but  they  show 
that,  when  properly  designed,  it  is  at  least  the  equal  of  the 
horizontal  boiler. 

The  three  cases  of  cast-iron  sectional  boilers,  viz.,  Nos.  61, 
62  and  63,  give  comparatively  poor  results.  The  unfavorable 
showing  is  due  in  some  degree  to  unfavorable  conditions.  In 
every  one,  the  ratio  of  heating  surface  to  grate  surface  is  below 
that  which  has  been  given  as  essential  to  economical  work.  In 
all  three  cases  the  effect  of  this  departure  from  correct  prin- 
ciples is  seen  in  the  high  degree  of  flue  temperature.  There 
is  nothing  in  the  construction  of  the  boiler  to  prevent  the 
employment  of  any  proportions  between  heating  surface  and 
grate  surface  which  may  be  desired,  and  it  is  not  improbable 
that  the  results  would  have  been  equal  to  those  of  the  tubular 
boiler  if  suitable  proportions  had  existed. 

There  is  some  variety  in  the  economic  results  produced  by 
the  water-tube  boilers.  Out  of  the  whole  number  of  boilers 
given,  amounting  in  all  to  nine,  only  one  appears  to  reach  the 
standard  laid  down  for  good  economy.  The  principal  results 
are  given  in  Table  No.  6.  Examining  these  figures  closely,  it 
is  seen  that  the  result  referred  to  (Boiler  No.  65,)  was  pro- 
duced by  boilers  having  a  sufficient  ratio  of  heating  surface  to 
grate  surface,  and  in  which  there  was  a  high  rate  of  combus- 
tion and  a  low  temperature  of  the  flue.  In  addition  to  this, 
the  boilers  were  comparatively  new.  These  are  conditions 
which,  as  already  shown,  usually  lead  to  high  performance. 
The  inferior  results  given  for  the  remaining  water-tube  boilers, 
with  one  exception,  can  be  attributed  to  waste  heat  at  the  flue. 
In  Boiler  No.  69,  the  high  temperature  seems  to  be  due  to  a 
deficiency  in  the  quantity  of  heating  surface.  In  most  of  the 


COMPARISON   OF  DIFFERENT  KINDS    OF   BOILERS.       41 


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42  BOILER   TESTS. 

remaining  boilers,  it  appears  to  be  inefficiency  of  the  surface 
which  causes  loss,  and  this  may  be  attributed  either  to  deposit 
of  scale  on  the  interior  of  the  surface,  or  of  soot  and  kindred 
substances  on  the  exterior.  The  last  may  be  of  frequent  occur- 
ence  if  the  care  of  the  boiler  is  neglected,  more  especially 
since  the  exterior  surfaces  of  water-tube  boilers  are  difficult  of 
access,  and  are  usually  cleaned  only  by  the  use  of  a  jet  of 
steam.  On  the  whole,  the  water-tube  boilers  may  be  consid- 
ered to  be  equal  in  economy  to  the  tubular  boilers,  under  the 
conditions  of  comparison  determined  upon,  that  is,  when  the 
conditions  are  favorable  to  economy. 

It  should  be  noted  that  one  test  is  given  on  a  water-tube 
boiler  which  shows  an  exceptionally  high  performance.  This 
is  referred  to  in  Part  Second,  being  made  on  Boiler  No.  68. 
The  evaporation  obtained  is  13.01  pounds,  from  and  at  212 
degrees  per  pound  of  combustible.  The  indication  of  this 
single  instance  shows  high  possibilities  of  the  boiler,  though 
it  loses  much  of  its  force  in  view  of  the  greatly  inferior 
result  obtained  from  the  same  boiler  on  Test  No.  134,  made 
two  years  later. 

There  remains  the  single  Galloway  boiler,  which  was  tested 
with  Cumberland  coal.  Unfavorable  conditions  for  economy 
exist  here,  and  the  low  result  produced  is  no  diiferent  from 
what  would  be  expected.  According  to  the  principles  govern- 
ing economical  work  many  times  exemplified  in  this  discussion, 
there  were  disadvantages  on  every  hand,  and  the  test  furnishes 
no  guide  as  to  the  capabilities  of  this  form  of  boiler  when 
operated  under  favorable  conditions. 

The  general  conclusion  to  be  drawn  from  all  these  compari- 
sons is  that  the  economy  with  which  different  types  of  boilers 
operate  depends  much  more  upon  their  proportions  and  the 
conditions  under  which  they  work,  than  upon  their  type  ;  and, 
moreover,  that  when  these  proportions  are  suitably  carried 
out,  and  when  the  conditions  are  favorable,  the  various  types 
of  boilers  give  substantially  the  same  economic  result. 


COMPARISON  OF  DIFFERENT  KINDS   OF  FUEL.  43 

4.       COMPARISON    OF   DIFFERENT   KINDS    OF    FUEL. 

There  are  two  methods  of  treating  the  question  of  a  com- 
parison of  different  kinds  of  fuel.  One  method  determines 
the  relative  economy  of  the  various  fuels,  when  each  is  burned 
under  the  conditions,  regarding  type  and  arrangement  of  boiler, 
which  will  give  the  most  favorable  results.  The  other  method 
compares  the  various  results  obtained  when  the  fuels  are 
burned  in  the  same  boiler,  regardless  of  proportions  and 
regardless  of  the  special  adaptability  of  the  boiler  for  the 
economical  use  of  any  particular  kind  of  fuel.  The  true 
economy  of  a  fuel  depends  to  some  extent  upon  its  market 
price.  Changes  which  occur  from  time  to  time  in  the  relative 
market  prices  of  different  fuels,  make  one  fuel  the  most  eco- 
nomical at  one  time,  and  another  fuel  at  another  time.  It 
becomes  advisable,  on  that  account,  to  change  fuels  when  a 
sufficient  change  of  prices  occurs.  If  this  is  done,  it  is  not 
usually  practicable  to  make  any  material  alteration  in  the  boiler, 
and  as  a  consequence  one  design  of  boiler  must  answer  for  all 
kinds  of  coal.  It  is  for  this  reason  that  the  second  method 
alluded  to  is  the  one  selected  for  the  treatment  of  the  subject, 
being,  moreover,  the  one  to  which  most  of  the  tests  conform. 

A  comparison  is  first  made  on  the  basis  of  the  number  of 
pounds  of  water  evaporated  from  and  at  212  degrees  per  pound 
of  coal.  Anthracite  broken  coal  is  used  as  a  standard,  and  the 
comparison  is  made  by  determining  the  percentage  of  increase 
or  decrease  in  each  case  above  or  below  the  evaporation  with 
that  coal.  Table  No.  7  gives  a  summary  of  the  results  of 
those  tests  which  can  be  treated  in  this  manner. 


44 


BOILER    TESTS. 


TABLE  No.  7. 


NUMBER  DESIG- 
NATING TEST. 

Cumber- 
land (in- 
crease). 

Chest- 
nut (de- 
crease). 

Pea  (de- 
crease). 

Pea  and 
Dust   and 
Cumber- 
land (de- 

Pea and 
Dust   and 
Culm  (de- 
crease). 

Nova 
Scotia 
Culm    (de 
crease). 

crease). 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

7 

10 

_ 

_ 

_ 

_ 

_ 

9 

_ 

- 

_ 

14 

_ 

_ 

10 

_ 

- 

- 

_ 

- 

21 

27 

7 

_ 

_ 

_ 

_ 

_ 

28 

_ 

_ 

_ 

6 

_ 

_ 

35 

_ 

4 

_ 

_ 

_ 

_ 

36 

_ 

_ 

13 

_ 

_ 

_ 

38 

14 

_ 

- 

- 

- 

_ 

39 

_ 

_ 

_ 

*2 

_ 

_ 

50 

_ 

_ 

6 

_ 

_ 

_ 

51 

_ 

_ 

_ 

_ 

14 

_ 

72 

9 

- 

- 

- 

- 

- 

75 

8 

_ 

_ 

— 

— 

_ 

76 

_ 

_ 

_ 

*1 

- 

_ 

84 

20 

_ 

_ 

_ 

_ 

_ 

85 

_ 

_ 

- 

- 

2 

- 

87 

17 

_ 

_ 

_ 

_ 

_ 

88 

_ 

_ 

_ 

_ 

_ 

7 

110 

- 

- 

- 

4 

- 

- 

111 

17 

- 

- 

- 

- 

- 

Average, 

12.8 

4 

9.5 

4.2 

8 

14 

*  Increase. 

If  we  assume  an  evaporation  of  11.00  pounds  of  water  from 
and  at  212  degrees  per  pound  of  combustible  for  the  perform- 
ance of  anthracite  broken  coal,  which  seems  to  be  a  result  within 
easy  reach  in  good  practice,  and  farther  assume  11  per  cent,  for 
an  average  percentage  of  ash  in  such  coal,  the  above  compari- 
son will  be  applied  to  an  evaporation  of  9.79  pounds  of  water 
from  and  at  2 12^  degrees  per  pound  of  coal.  The  performance 
of  the  various  fuels,  expressed  in  pounds  of  water  evaporated 
per  pound  of  dry  coal,  will  then  be  as  follows  :  — 


COMPARISON  OF  DIFFERENT  KINDS   OF  FUEL. 


45 


NAME  OF  COAL. 


Water  from  and 
at  212  degrees 


of 


per Ib. 
dry   coal. 


Anthracite  broken, 

Cumberland, 

Anthracite  Chestnut,         .         .         .         .   .     '.    . 
Anthracite  Pea,         .         .         .         .         .         *' 
Two  parts  Pea  and  Dust  and  one  part  Cumberland 
Two  parts  Pea  and  Dust  and  one  part  Culm, 
Nova  Scotia  Culm,    ....        V.    ."•: 


Lbs. 
9.79 
11.04 
9.40 
8.86 
9.38 
9.01 
8.42 


These  figures  apply  to  dry  coal.  The  tine  grades  of  anthra- 
cite coal  and  the  bituminous  coals  are  frequently  moist  from 
exposure  to  the  weather.  In  the  moist  or  even  wet  condition 
which  exists  when  the  purchaser  buys  coal,  this  comparison 
does  not  indicate  the  true  relative  performance.  The  quantity 
of  moisture  which  such  coal  contains  is  uncertain  and  variable. 
Three  per  cent,  may  be  allowed  for  an  average,  but  in  indi- 
vidual cases  it  may  run  up  to  6  per  cent,  or  more.  While 
this  allowance  serves  to  reduce  the  evaporation  with  the  coals 
named,  the  coarse  grades  of  anthracite  coal  in  practice  require 
an  allowance  which,  though  of  different  nature,  operates  in  the 
same  manner.  The  figures  of  the  tests  are  based  on  the  weight 
of  coal  obtained  by  deducting  unconsumed  fuel  left  at  the  end 
of  the  test,  and  no  deduction  of  much  consequence  requires  to 
be  made  except  when  the  large  grades  of  anthracite  coal  are 
used.  In  the  practical  work  of  operating  boilers  much  of  this 
unconsumed  coal  is  thrown  away  with  the  ashes.  It  readily 
amounts  to  3  per  cent.,  and  this  corresponds  to  the  allowance 
which  with  other  fuels  may  be  made  for  moisture.  The  quan- 
tities given  may  therefore  be  used,  as  they  stand,  for  purposes 
of  comparison,  although  taken  individually  they  do  not  show 
precisely  the  work  of  the  various  fuels  in  the  conditions  in 
which  they  are  bought  and  used. 

In  the  comparison  of  relative  quantity  of  water  evaporated 
by  the  different  fuels,  it  is  seen  that  Cumberland  coal  easily 
takes  the  lead.  As  Table  No.  7  shows,  the  evaporation  of  this 
coal  is  12.8  per  cent,  more  than  that  of  anthracite  coal.  In 


46  BOILER    TESTS. 

the  other  cases  the  evaporation  is  less  than  that  of  anthracite 
coal;  that  of  chestnut  coal  is  4  per  cent,  less;  pea  coal  9.5 
per  cent.  ;  mixture  of  pea  and  dust  and  Cumberland  4.2  per 
cent.  ;  mixture  of  pea  and  dust  and  culm  8  per  cent. ;  Nova 
Scotia  culm  14  per  cent. 

Proceeding  farther,  let  us  examine  the  subject  from  the 
financial  standpoint  and  make  a  comparison  on  the  basis  of 
cost.  Two  elements  must  be  considered  here,  viz.,  cost  of 
fuel  and  cost  of  labor ;  both  vary  for  the  different  fuels. 
Take  the  case  of  a  plant  of  1 ,000  horse-power.  According  to 
the  standard  of  horse-power  used  in  the  paper,  the  daily  pro- 
duct of  steam  for  ten  hours'  run  of  such  a  plant  is  344,721 
pounds,  assumed  to  be  evaporated  from  and  at  212  degrees. 
The  number  of  tons  of  the  various  kinds  of  coal  used  per  day, 
computed  from  this  quantity,  are  given  in  Table  No.  8.  This 
table  also  contains  the  prices  of  the  various  coals,  found  by 
taking  an  average  of  the  present  (October,  1888,)  quotations 
for  a  cargo  delivered  in  the  cities  of  Lawrence,  Fall  Kiver  and 
Waltham ;  and  farther,  the  total  cost  of  coal  for  one  day's  run 
at  the  prices  named.  The  table  also  gives  the  cost  of  labor 
required  in  firing,  the  assumption  being  made  in  the  case  of 
anthracite  coal  of  broken,  chestnut  or  pea  sizes,  that  the  labor 
is  performed  by  two  day  firemen,  one  night  fireman  and  two 
helpers,  and  in  the  case  of  bituminous  coals  that  one  additional 
fireman  is  required;  while  in  that  of  the  mixed  fuels,  one 
fireman  and  one  helper  additional  are  required.  The  wages  of 
the  firemen  are  assumed  to  be  $1.75  per  day,  and  of  helpers 
$1.25  per  day.  Finally,  the  table  gives  the  total  cost  of  fuel 
and  labor  for  the  day's  run  of  ten  hours,  computed  in  accord- 
ance with  the  assumptions  named. 

It  appears  from  Table  No.  8  that  at  the  prices  named  there 
is  a  difference  in  the  cost  of  coal  and  labor  for  a  day's  run  on 
a  1,000  horse-power  plant,  reckoned  between  the  highest  and 
lowest  quantities,  of  $41.27.  The  significance  of  this  sum  is 
apparent  when  it  is  considered  that  in  a  year's  time  it  repre- 
sents $12,711.  Such  a  sum  has  no  small  relation  to  the  total 
amount  of  profit  which  a  mill  employing  a  1 ,000  horse-power 
plant  realizes. 


COMPARISON  OF  DIFFERENT  KINDS   OF  FUEL. 


47 


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48  BOILER    TESTS. 

The  highest  cost  in  the  comparison  attends  the  use  of  anthra- 
cite chestnut  coal,  and  the  lowest  that  of  a  mixture  of  two 
parts  pea  and  dust  and  one  part  Nova  Scotia  culm.  The  pure 
Nova  Scotia  culm  stands  about  on  a  par  with  the  mixture. 

If  the  Nova  Scotia  coal  and  the  mixture  containing  Nova 
Scotia  coal  are  left  out  of  the  comparison,  the  mixture  of  pea 
and  dust  and  Cumberland  coal  takes  the  lead  as  the  cheapest 
fuel,  and  the  Cumberland  follows  closely  upon  it.  These 
figures  show  that  at  prices  which  now  hold,  little  is  gained  by 
the  use  of  a  mixture  of  either  pea  and  dust  and  Cumberland  or 
of  pea  and  dust  and  culm.  Either  of  the  bituminous  coals 
fired  without  mixture  produces  nearly  as  good  results.  Con- 
sidering the  fact  that  the  use  of  the  mixed  fuel  reduces  the 
available  power  of  the  boiler,  the  pure  coal  easily  has  the 
advantage  ;  no  one  would  go  to  the  trouble  of  using  an  inferior 
grade  of  coal,  such  as  the  best  pea  and  dust  mixed  with 
bituminous  coal  is,  and  such  as  much  of  it  is  liable  to  be, 
unless  by  so  doing  a  material  reduction  in  cost  could  be 
attained.  If  yard  screenings  can  be  delivered  at  $2.75  per 
ton,  and  if  it  secures  the  same  result  as  pea  and  dust  coal,  the 
total  cost  of  fuel  and  labor  when  a  mixture  of  two  parts 
screenings  and  one  part  Cumberland  coal  is  used  amounts  to 
$65.69  per  day,  and  this  sum  is  lower  than  any  quantity  given 
in  the  table. 

Pea  coal  conies  next  to  Cumberland  in  the  order  of  cheap- 
ness, though  the  difference  is  trifling,  and  then  the  anthracite 
broken  coal. 

An  important  matter  relating  to  -the  use  of  different  kinds  of 
coal  is  the  relative  amount  of  power  which  they  give  when 
fired  in  the  same  boiler.  Boiler  No.  5j  rated  at  54  horse- 
power (on  the  basis  of  12  square  feet  of  heating  surface),  gave 
60  horse-power  with  Cumberland  coal,  53.9  horse-power  with 
anthracite  broken,  and  38.5  horse-power  with  a  mixture  of 
two  parts  pea  and  dust  and  one  part  Cumberland,  the  damper 
being  wide  open  in  every  case.  Boiler  No.  9,  rated  at  74 
horse-power  with  3-8  inch  draught  suction,  gave  143.8  horse- 
power with  Cumberland  coal,  105.5  horse-power  with  anthra- 


COMPARISON  OF  DIFFERENT  KINDS   OF  FUEL.  49 

cite  egg,  and  95.1  horse-power  with  a  mixture  of  equal  parts 
of  screenings  and  Cumberland  coal.  Boiler  No.  12,  rated  at 
87  horse-power,  gave  84  horse-power  with  anthracite  broken 
coal,  105.4  horse-power  with  Cumberland,  and  82.2  horse- 
power with  a  mixture  of  two  parts  screenings  and  one  part 
Cumberland,  The  draught  was  0.28  inches.  Boiler  No.  17, 
rated  at  129  horse-power,  gave  192.3  horse-power  with  anthra- 
cite broken  coal,  draught  0.11  inches;  149.2  lurse-power 
with  pea  coal,  draught  0.12  inches;  and  157.1  horse-power 
with  44  parts  pea  and  dust  and  37  parts  culm,  draught  0..28 
inches.  Vertical  boiler  No.  54,  rated  at  140  horse-power, 
gave  94  horse-power  with  Cumberland  coal,  draught  0.07 
inches ;  103.8  horse-power  with  anthracite  broken,  draught 
0.05  inches;  and  118.1  horse-power  with  two  parts  screenings 
and  one  part  Cumberland,  draught  0.32  inches.  Boiler  No. 
36,  rated  at  270  horse-power,  gave  196.1  horse-power  with 
anthracite  broken  coal,  draught  0.25  inches;  214.6  horse- 
power with  Cumberland  coal,  draught  0.20  inches ;  and  204.8 
horse-power  with  6  parts  screenings  and  4  parts  Cumberland, 
draught  0.31  inches.  It  is  seen,  therefore,  that  as  regards 
capacity,  Cumberland  coal  secures  the  largest  power  with  a 
given  draught,  and  pea  coal  or  mixtures  of  screenings  and 
bituminous  coal  the  least.  This  suggests  that  to  secure  the 
same  capacity  from  a  given  boiler  with  different  kinds  of  coal, 
the  area  of  grate  surface  must  be  varied  to  suit  the  varied 
kinds  of  coal.  In  the  case  of  Boiler  No.  9,  for  example,  the 
grate  would  have  been  increased  in  the  proportion  of  95.1  to 
143.8  when  the  mixed  fuel  was  used,  in  order  to  bring  the 
amount  of  power  developed  up  to  that  obtained  with  Cumber- 
land coal. 

Among  the  tests  given  in  the  paper  are  a  few  made  with 
other  kinds  of  niel  than  those  upon  which  the  comparisons  are 
made. 

There  are  several  with  «  chestnut  No.  2"  anthracite,  which 
corresponds  in  size  to  the  pea  grade.  The  evaporation,  and 
the  cost  also,  are  about  the  same  as  with  pea  coal. 

Two  tests   are  given  where  Walston  bituminous  coal  was 


50  BOILEE    TESTS. 

used.  These  were  made  on  boilers  No.  34  and  No.  39,  and  the 
conclusion  drawn  from  the  results  is  that  this  coal  under  favor- 
able circumstances  gives  about  the  same  evaporation  per 
pound  of  fuel  as  anthracite  broken  coal. 

From  the  indication  of  a  single  test,  made  on  Boiler  No.  37, 
the  performance  of  Ohio  lump  coal  with  favorable  conditions 
appears  to  fall  about  5  per  cent,  below  the  economy  of  anthra- 
cite broken  coal. 

Two  tests  are  given  which  show  the  performance  of  coke, 
that  is,  the  refuse  coke  of  gas  retorts  used  in  the  manufacture 
of  illuminating  gas.  Test  No.  95,  made  with  coke  on  a  plain 
cylinder  boiler,  gave  8  per  cent,  less  evaporation  per  pound  of 
fuel  than  anthracite  pea.  Test  No.  67,  made  with  coke  on  a 
horizontal  tubular  boiler,  gave  14.7  per  cent,  less  evaporation 
per  pound  of  fuel  than  a  high  grade  of  Cumberland  coal.  The 
cost  of  the  coke  was  $3.00  for  2,000  pounds. 

Three  tests  give  information  upon  the  use  of  petroleum  for 
fuel.  Test  No.  24,  made  with  petroleum,  under  somewhat 
unfavorable  conditions,  gave  an  evaporation  of  11.96  pounds 
of  water  from  and  at  212  per  pound  of  petrojeum.  Test  No. 
77  with  "  residuum"  of  petroleum  gave  13.66  pounds.  A 
test  with  Canadian  oil  gave  15.00  pounds.  Suppose  the  last 
figure  can  be  realized  in  good  practice.  At  this  rate,  the 
quantity  of  oil  required  to  produce  1,000  horse-power  for  a 
day's  run  of  ten  hours  (344,721  pounds  from  and  at  212 
degrees)  is  22,981  pounds,  or  3,536  gallons  (1  gallon  =  6.5 
pounds).  The  price  of  oil  per  gallon,  required  to  make  the 
cost  for  a  day's  run  equal  to  that  of,  say  Cumberland  coal, 
may  be  figured  from  Table  No.  8.  The  total  cost  of  fuel  and 
labor  given  for  Cumberland  coal  (the  price  being  $4.56  per 
ton)  is  $72.88.  The  cost  of  labor  when  oil  is  used  is  reduced 
to,  say  one  man  at  $2.00  per  day  and  a  helper  at  $1.25, 
making  a  total  of  $3.25.  Substract  this  from  $72.88  and  there 
is  left  for  the  cost  of  fuel  $69.63,  which  is  1^  cents  per 
gallon  of  petroleum,  or  98.5  cents  per  barrel  of  50  gallons. 
This  means,  in  round  numbers,  that  the  price  of  oil  must  be 
less  than  one  dollar  per  barrel,  delivered  at  the  boiler,  in 


EFFECT  OF  DIFFERENT  FOEMS  OF  SETTING.  51 

order  that  the  cost  of  fuel  and  labor  for  a  1,000  horse-power 
plant  shall  be  equal  to  that  which  obtains  when  Cumberland 
coal  is  used  at  $4.56  per  ton. 

If  the  economic  result  with  petroleum  goes  up  to  18  pounds, 
the  price  of  oil  per  barrel  to  equal  Cumberland  coal  on  this 
basis  is  $1.18  cents.  It  is  to  be  noted  that  these  figures  are 
based  upon  a  barrel  of  50  gallons.  If  the  barrel  is  taken  to 
be  42  gallons,  the  prices  become  82.7  cents  for  an  evaporation 
of  15  pounds,  and  99.1  cents  for  an  evaporation  of  18  pounds. 

5.       MISCELLANEOUS    DISCUSSION. 

The  general  subject  of  boiler  economy  has  now  been  exam- 
ined, so  far  as  it  is  affected,  first,  by  the  character  of  the  steam, 
that  is,  as  to  its  being  saturated  or  superheated;  second,  by 
the  general  arrangement  of  the  heating  surface  and  the  condi- 
tions under  which  the  boiler  is  worked ;  third,  by  the  type  of 
the  boiler ;  and  fourth,  by  the  character  of  the  fuel  burned. 
These  may  be  regarded  as  the  more  noteworthy  divisions  of 
the  subject.  Incidental  matters  remain  to  be  taken  up,  and 
these  are  quite  as  interesting,  and  sometimes  almost  as  import- 
ant, as  the  main  questions  thus  far  considered. 

An  important  question  connected  with  the  economy  of 
boilers  is  that  of  the  effect  which  the  form  of  setting  has, 
where  the  boiler  is  externally  fired.  Questions  arise  in  the 
setting  of  horizontal  tubular  boilers  as  to  the  distance  between 
the  grate  and  the  shell,  and  between  the  top  of  the  bridge  wall 
and  the  shell ;  the  shape  of  bridge  wall,  whether  curved 
upward  to  conform  to  the  curve  of  the  shell,  or  simply  left 
flat;  the  arrangement  of  the  front  of  the  bridge  wall,  whether 
inclined  or  vertical ;  and  the  arrangement  of  the  space  behind 
the  bridge  wall.  Although  the  tests  furnish  no  direct  compar- 
ative data  on  these  subjects,  useful  information  may  be  drawn 
from  individual  results.  It  is  significant  that  the  highest 
results  given  are  in  some  cases  obtained  with  one  form  of 
setting  and  in  some  with  another  form.  Boiler  No.  9,  which 
gave  a  high  result  with  anthracite  coal,  has  a  flat  bridge  wall 
with  perpendicular  front,  and  the  space  behind  the  bridge  is 


52  BOILEE    TESTS. 

partially  filled.  Boiler  No.  10,  which  also  gave  a  high  result 
with  anthracite  coal,  has  a  curved  bridge  wall  with  vertical 
front,  and  the  space  behind  is  filled  so  as  to  conform  to  the 
same  curve.  Boiler  No.  12  is  another  case  in  point,  and  here 
the  bridge  wall  is  flat  with  a  vertical  front,  and  the  space 
behind  is  filled  in  so  as  to  provide  an  inclined  bed  leading 
down  to  a  deep  chamber  at  the  rear  end.  Boiler  No.  35, 
which  gave  a  good  result,  if  allowance  is  made  for  the  high 
temperature  of  the  gases,  has  a  flat  bridge  wall  with  perpendi- 
cular front,  and  the  space  behind  is  filled  to  an  even  level  with 
the  top.  Boilers  No.  13  and  No.  16,  using  inferior  grades  of 
anthracite  coal,  showed  favorable  results,  and  the  bridge  walls 
are  flat  with  vertical  fronts  and  the  space  in  the  rear  is  open 
in  both  cases.  Passing  to  boilers  using  Cumberland  coal,  No. 

31  and  No.  32,  which  give  high  results,  both  have  vertical  walls  ; 
No.  31  is  curved  at  the  top,  with  open  space  behind,  and  No. 

32  is  flat  with  open  space,  the  latter  being  provided  Avith  a 
second  Avail  at  the  rear  end  of  the   boiler.     It  would  appear 
from  these  examples  that  the  general  form  of  the   setting  in 
respect  to  the  particulars  named  may  be  one  thing  or  another, 
and  the  boiler  still  give  the  highest  economy.     This  furnishes 
strong  ground  for  the  conclusion  that  the  matter  is  of  compar- 
atively little  importance,  and  that  the  plan  to  be  followed  is 
the  one  which  will  secure  the  simplest,  and  at  the  same  time 
the  most  convenient  arrangement. 

The  tests  give  some  very  pointed  indications  regarding  the 
effect  of  admitting  air  into  the  furnace  above  the  fire.  Many 
of  the  settings  are  arranged  with  a  view  to  this  special  object. 
A  current  of  air  in  a  finely  divided  state  is  introduced  into  the 
furnace  so  as  to  mingle  with  the  products  of  combustion  as 
they  emerge  from  the  burning  coal. 

The  simplest  method  followed  is  to  conduct  the  air  directly 
from  the  outside  to  the  interior  of  the  bridge  wall,  which  is 
made  hollow,  and  to  discharge  it  through  perforations  in  the 
top  covering  of  the  wall,  which  may  be  either  iron  or  brick. 
The  air  thus  supplied  mingles  with  the  lower  strata  of  burning 
gas  as  it  skims  over  the  bridge.  Boiler  No.  15  was  arranged 


ADMISSION  OF  AIR   OVEE  FUEL.  53 

according  to  this  method,  and  tests  Nos.  40  to  45  were  con- 
ducted with  a  view  to  determining  the  effect  which  the  admis- 
sion of  air  has  upon  the  economy  of  the  boiler,  three  different 
kinds  of  coal  being  used.  The  coals  were  Cumberland,  anthra- 
cite broken  and  a  mixture  of  two  parts  pea  and  dust  and  one 
part  Cumberland.  The  air  was  supplied  to  the  bridge  wall 
through  an  opening  having  an  area  of  38.5  square  inches, 
which  is  1.4  square  inches  for  one  square  foot  of  grate  surface. 
When  Cumberland  coal  was  used  the  full  opening  of  this  area 
was  employed ;  when  anthracite  coal  and  the  mixture  were 
used  the  opening  was  contracted  about  one-half,  thus  present- 
ing an  area  of  0.7  square  inches  for  one  square  foot  of  grate. 
There  is  a  wide  difference  in  the  effect  of  admitting  air  in  the 
different  cases.  In  the  case  of  Cumberland  coal,  the  evapora- 
tion is  increased  5.9  per  cent,  per  pound  of  coal,  and  6.2  per 
cent,  per  pound  of  combustible ;  that  of  anthracite  coal  is 
decreased  one  per  cent,  per  pound  of  combustible  and  is  about 
the  same  per  pound  of  coal ;  that  of  the  mixed  fuel  is  decreased 
2  per  cent,  per  pound  of  coal  and  4.7  per  cent,  per  pound  of 
combustible.  The  effect  which  the  introduction  of  air  had 
upon  the  appearance  of  the  products  of  combustion,  as  viewed 
by  an  observer  at  the  "  peek  hole  "  back  of  the  bridge  wall, 
was  very  noticeable  in  every  case.  It  was  greatest,  to  be 
sure,  with  Cumberland  coal,  but  the  heightened  color  and  the 
increased  activity  of  the  flame  produced  by  the  entrance  of  air 
was  plainly  to  be  seen  whichever  fuel  was  used. 

It  is  to  be  noted  that  an  apparent  benefit  was  realized  in  the 
case  of  both  the  anthracite  coal  and  the  mixed  fuel  when 
judged  by  the  improved  state  of  combustion  which  the  eye 
beheld.  In  reality,  however,  there  was  a  loss,  and  this  goes 
to  show  that  the  ocular  method  of  judging  in  these  matters  is 
liable  to  be  deceptive. 

In  these  tests  another  effect  was  produced  by  the  admission 
of  air.  The  quantity  and  density  of  the  smoke  issuing  from 
the  chimney  was  reduced.  This  was  most  marked  with  Cum- 
berland coal,  which  gave  the  most  smoke.  When  air  was 
excluded,  smoke  was  visible  ^^}  of  the  time ;  when  air  was 


5t  BOILER   TESTS. 

admitted,  the  smoke  was  visible  70.  of  the  time.  In  the 
case  of  the  mixed  fuel  little  smoke  was  produced  in  either 
case. 

A  second  method  of  admitting  air  which,  though  not  so 
simple,  is  rather  more  effective  than  that  just  named,  is  the  one 
applied  to  Boiler  No.  9.  Here  the  air  is  supplied  iirst  to  a 
pipe  laid  in  the  bridge  wall,  and  then  to  perforated  cast-iron 
globes  which  rest  upon  the  top  of  the  wall.  This  method  is 
rendered  more  effective  than  the  first  by  the  more  thorough 
mixture  which  it  secures  between  the  incoming  air  and  the 
burning  gases.  The  quantity  of  air  supplied  is  increased 
above  that  naturally  drawn  in  by  means  of  a  jet  of  steam. 
The  steam  thus  supplied  mingles  with  the  air.  In  this  case  the 
effect  of  admitting  air  above  the  fuel,  when  Cumberland  coal 
was  burned,  was  to  increase  the  evaporation  per  pound  of  coal 
8.4  per  cent.,  and  per  pound  of  combustible  8  per  cent.  It 
may  be  added  that  a  test  made  with  Lehigh  coal,  not  recorded, 
showed  that  with  this  fuel  the  admission  of  air  was  attended 
by  an  increase  of  evaporation  of  1.9  per  cent,  per  pound  of 
coal  and  3.7  per  cent  per  pound  of  combustible. 

A  third  method  of  admitting  air,  which  is  more  efficient 
than  either  of  the  first  two,  is  that  applied  to  Boiler  No.  40. 
It  consists  in  supplying  one  current  of  air  through  the  bridge 
wall  by  means  of  perforations  in  the  rear  face  of  the  wall  near 
the  top,  and  another  current  of  air  through  a  secondary  wall 
placed  a  short  distance  to  the  rear  of  the  bridge  wall,  and 
elevated  so  as  to  close  up  the  passage  between  it  and  the  shell 
of  the  boiler,  and  make  the  products  of  combustion  descend 
and  pass  beneath  it.  The  second  current  of  air  discharges 
through  perforations  in  the  front  face  of  the  hanging  wall.  By 
these  provisions  the  entering  air  is  thoroughly  diffused  through 
the  whole  volume  of  burning  gas.  The  only  test  made  on  this 
boiler  was  with  the  air  admitted,  and  there  is  consequently  no 
positive  information  as  to  the  economy  of  this  method.  There 
is  indirect  evidence,  however,  pointing  to  its  superiority,  in  the 
fact  that  the  result  of  the  test  was  most  excellent,  being  12.47 
pounds  of  water  from  and  at  212  degrees  per  pound  of  com- 


ADMISSION  OF  AIR    OVER   FUEL.  55 

bustible,  and  this  is  the  highest  given  in  the  paper  for  horizon- 
tal tubular  boilers. 

A  fourth  method  consists  in  first  passing  the  air  back  and 
forth  through  passages  running  lengthwise  of  the  walls  of  the 
setting  and  then  discharging  it  through  perforations,  part  of 
which  are  located  on  the  top  of  the  bridge  wall  and  part  on  the 
two  sides  of  the  furnace.  The  object  sought  is  to  supply  the 
air  in  a  somewhat  heated  condition.  Several  tests  are  given 
which  show  the  effect  of  this  method.  Tests  No.  11  and  No.  12 
were  made  for  this  purpose.  A  mixture  of  two  parts  pea  and 
dust  and  one  part  Nova  Scotia  culm  was  used,  and  in  one  test 
air  was  supplied  through  the  registers  in  the  fire-doors,  and  in 
the  other  through  the  passages  in  the  walls.  The  use  of  the  air 
passages  secured  an  increased  evaporation  of  2  per  cent,  per 
pound  of  coal,  while  the  result,  when  figured  on  combustible, 
was  the  same  in  both  cases.  Vertical  boiler  No.  54  is  provided 
with  air  passages  running  up  and  down  in  the  circular  wall  of 
the  setting,  and  discharging  at  numerous  points  over  the  fire 
through  perforations.  Test  No.  109,  made  on  this  boiler  with 
air  admitted,  gave  4.3  per  cent,  less  evaporation  per  pound  of 
coal  and  2.3  per  cent,  less  per  pound  of  combustible,  than  test 
No.  110,  made  with  air  excluded.  The  fuel  was  a  mixture  of 
two  parts  anthracite  screenings  and  one  part  Cumberland  coal. 
Boiler  No.  20,  in  which  air  was  admitted  in  accordance  with 
this  method,  compared  with  an  exactly  similar  boiler  (No.  21) 
in  which  air  was  not  admitted,  fired  with  a  mixture  of  three 
parts  pea  and  dust  and  one  part  Cumberland  coal,  gave  4.5 
per  cent,  less  evaporation  per  pound  of  coal  and  4.7  per  cent, 
less  per  pound  of  combustible.  Boiler  No.  27,  with  air 
admitted  and  fired  with  Nova  Scotia  coal,  gave  1  per  cent, 
higher  evaporation  per  pound  of  coal  and  1.5  per  cent,  higher 
evaporation  per  pound  of  combustible  than  Boiler  No.  26, 
which  was  precisely  similar,  except  that  no  provisions  were 
made  for  admitting  air  through  the  walls.  In  both  of  these 
cases  the  registers  in  the  fire-doors  were  open.  They  pre- 
sented an  open  area  of  22  square  inches,  or  one-fourth  of  one 
square  inch  for  one  square  foot  of  grate  surface.  The  openings 


56  BOILEE    TESTS 

to  the  passages  in  the  walls  presented  an  area  of  32  square 
inches,  or  about  four-tenths  of  one  square  inch  for  one  square 
foot  of  grate.  This  proportion  is  only  about  one-fourth  of 
that  provided  in  the  case  first  noticed  (Boiler  No.  15),  where 
the  admission  of  air  to  Cumberland  coal  gave  about  6  per  cent, 
advantage. 

The  conclusion  drawn  from  these  examples  is  that  a  consid- 
erable advantage  attends  the  admission  of  air  above  the  fuel 
when  bituminous  coal  is  employed,  the  amount  of  gain  depend- 
ing somewhat  upon  the  method  employed.  There  is  no  advan- 
tage in  the  system  when  mixtures  of  anthracite  screenings  and 
bituminous  coal  are  used,  if  carried  out  according  to  either  the 
first  or  fourth  methods  ;  and,  finally,  little  or  no  benefit  is 
derived  when  anthracite  coal  is  burned. 

FLUE    HEATERS. 

Another  question  connected  with  the  general  subject  of  the 
boiler  economy,*  is  that  of  the  economy  produced  by  the 
employment  of  a  feed-water  heater  in  the  flue,  and  the  tests 
show  that  this  may  be  of  considerable  importance.  That  the 
use  of  a  flue  heater,  in  connection  with  a  boiler  having  too  little 
heating  surface,  and  sending  a  high  degree  of  waste  heat  into 
the  chimney,  is  productive  of  economy,  no  one  can  have  good 
reason  to  doubt ;  and  this  is  clearly  shown  by  the  results  of 
tests  No.  121  and  No.  122,  which  are  cases  in  point,  where  a 
temperature  of  618  degrees  existed,  and  the  heater  added  29 
per  cent,  to  the  evaporation  per  pound  of  coal.  The  special 
interest  in  the  question  is  not  in  cases  like  this,  where  the 
waste  heat  is  due  to  defects  in  the  design  and  operation  of 
the  boiler,  but  rather  in  cases  of  reasonably  good  practice, 
where  the  temperature  of  the  flue  is  not  what  may  be  regarded 
as  excessive.  There  are  a  number  of  such  cases  given,  and 
the  general  results  produced  are  repeated  in  Table  No,  9. 


FLUE  HEATEE8. 
TABLE  No.   9.  —  Tests  with  Flue  Heaters. 


57 


1.  Number  of  boiler, 

33 

46 

62 

68 

2.  Area  of  heating  surface,  boiler, 

sq.  ft. 

1,894 

4,058 

5,592 

3,126 

3.  Area  of  heating  surface,  heater, 

sq.  ft. 

1,600 

1,920 

1,280 

1,600 

4.  Temperature  of     gases    leaving 

boiler,  ....          deg. 

376 

361 

403 

435 

5.  Temperature  of     gases    leaving 

heater,          .        .       ..         deg. 

231 

254 

299 

279 

6.  Temperature  of  feed-water  enter- 

ing heater,    .        .        .         deg. 

95 

79 

111 

84 

7.  Temperature  of  feed-water  enter- 

ing boiler,    .         .        .          deg. 

175 

145 

169 

196 

8.  Increased  evaporation  produced 

by  heater,     .        .        .  per  cent. 

10.5 

7 

9.3 

12.8 

The  average  results  of  these  four  trials  show  that  the  use  of 
a  flue  heater  having  44  per  cent,  as  much  heating  surface  as 
that  of  the  boiler,  applied  where  the  temperature  of  the  escap- 
ing gases  is  394  degrees  and  the  initial  temperature  of  the 
feed-water  92  degrees,  increases  the  evaporation  per  pound  of 
coal  9.9  per  cent.  The  important  question  which  arises  is, 
does  this  amount  of  gain  pay  for  the  addition  to  the  plant 
involved  by  the  employment  of  this  apparatus?  Let  us  refer 
the  matter  to  a  plant  of  1 ,000  horse-power,  and  use  for  a  cal- 
culation the  cost  of  Cumberland  coal  required  for  a  day's  run 
of  10  hours,  given  in  Table  No.  8,  which  is  $63.38.  The 
saving  produced  by  the  flue  heater  is  $5.71  per  day,  and  this 
amount  represents  for  a  year  of  308  days  a  total  saving  of 
$1,759.  The  cost  of  a  heater  with  complete  equipment  of 
setting  and  appurtenances,  having  a  surface  of  say  5,000 
square  feet,  which  corresponds  to  the  instances  referred  to,  is 
$7,000  to  $8,000.  The  economy  secured  is,  therefore,  suffici- 
ent to  pay  a  yearly  return  of  from  20  per  cent,  to  25  percent, 
on  the  additional  investment,  which  is  certainly  of  some 
importance. 

It  must  be  borne  in  mind  that  this  result  applies  only  to  a 
case  where  the  temperature  of  the  water  supplied  to  the  heater 
is  comparatively  low,  corresponding  to  that  of  the  overflow 
water  of  a  condensing  engine.  On  the  other  hand,  it  is  a  case 


58  BOILER   TESTS. 

where  the  temperature  of  the  flue  is  not  far  from  that  laid 
down  in  another  part  of  the  paper  for  boilers  giving  most 
economical  results,  and  it  is  seen  from  the  many  instances 
recorded  that  the  exigencies  of  boiler  work  often  bring  about  a 
much  higher  flue  temperature.  The  flue  heater  thus  has  a 
useful  place,  not  only  in  a  few  instances  but  in  a  large  majority 
of  boiler  plants  where  the  water  is  supplied  in  a  comparatively 
cold  state.  In  the  cases  given,  there  is  a  reduction  of  128 
degrees  in  the  temperature  of  the  gases,  and  an  increase  of  79 
degrees  in  the  temperature  of  the  water.  Each  one  per  cent, 
added  to  the  evaporation  corresponds  to  a  reduction  of  about 
13  degrees  in  the  temperature  of  the  escaping  gases. 

It  is  important  to  note  the  effect  which  the  use  of  the  heater 
has  upon  the  draught.  The  amount  of  draught  suction  which 
existed  in  some  of  the  above  examples  and  in  one  additional 
example,  together  with  information  regarding  quantity  of  coal 
burned  and  other  matters  bearing  on  the  question,  are  given  in 
Table  No.  10. 

The  effect  of  a  reduced  temperature  of  the  escaping  gases, 
which  always  accompanies  the  employment  of  the  heater,  is 
seen,  in  every  one  of  these  instances,  to  reduce  the  draught 
power  of  the  chimney.  In  Boiler  No.  59  the  temperature  is 
reduced  from  645  degrees  to  365  degrees,  and  the  draught 
from  f^Q  of  an  inch  to  ffi0  of  an  inch,  or  22  per  cent.  This 
is  with  an  80-foot  chimney.  In  the  last  case  a  reduction  of 
temperature  from  575  degrees  to  373  degrees  is  accompanied 
by  a  reduction  of  draught  from  £J0  of  an  inch  to  ff(}  of  an 
inch,  or  29  per  cent.  This  is  with  a  140-foot  chimney. 
Although  the  general  effect  of  the  flue  heater  in  this  respect  is 
unfavorable,  a  larger  amount  of  draught  is  required  to  operate 
the  boiler, in  every  instance  where  the  average  draught  is  given, 
when  the  heater  is  thrown  out  of  use.  This  is  not  due  to  any 
peculiar  action  of  the  heater  but  evidently  to  the  increased 
quantity  of  coal  which  must  be  burned  in  order  to  make  up  for 
its  absence.  It  may  be  concluded  that  a  plant  of  boilers  work- 
ing to  the  full  capacity  of  the  chimney  without  a  heater,  will 
have  no  difficulty  in  producing  the  same  amount  of  steam, 


FLUE  HEATERS. 


59 


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•rH    "•" 

•rH    .— 

Number  of  boiler,  . 

Height  of  chimney, 

Conditions,  . 

I 
1 

Temperature  gases 
tering  chimney,  < 

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inside  damper,  . 

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60  BOILER   TESTS. 

working  with  a  heater,  unless  the  temperature  of  the  gases  is 
excessive.  If  the  temperature  is  excessive  and  the  full  capac- 
ity of  the  chimney  is  required,  there  is  some  doubt  whether  a 
heater  could  successfully  be  used. 

The  quantities  given  in  Table  No.  10  show  the  draught 
power  of  chimneys  of  different  heights,  supplied  with  gas  of 
various  temperatures.  In  this  connection  it  may  be  added 
that  the  draught  of  another  chimney  having  a  height  of  230 
feet,  supplied  with  gas  at  a  temperature  of  500  degrees, 
amounted  to  1.6  inches.  This  and  all  the  observations  referred 
to  were  made  in  cold  weather. 

The  effect  of  changing  the  proportions  of  air  space  in  the 
grates  is  shown  by  the  tests  on  Boiler  No.  10.  With  anthra- 
cite Lehigh  coal,  of  which  8.7  pounds  were  consumed  per 
square  foot  of  grate  per  hour,  the  grates  having  50  per  cent, 
air  space,  secured  about  2  per  cent,  more  evaporation  per 
pound  of  combustible  than  those  having  60  per  cent,  air  space. 
With  about  one-half  as  much  coal  burned  in  a  given  time  the 
gain  was  8  per  cent,  in  favor  of  the  smaller  air  space.  The 
results  of  repeated  tests  corroborated  these  figures.  Consider- 
ing that  whatever  air  passes  through  the  grate,  beyond  that 
needed  for  chemically  perfect  combustion,  produces  a  loss  of 
economy,  and  that  an  excess  of  air  to  a  greater  or  less  extent 
always  attends  combustion,  the  effect  may  be  explained  on  the 
ground  that  the  reduced  amount  of  opening  in  the  grates,  tends 
to  cut  off  this  source  of  waste.  The  effect  appears  to  be 
greatest  when  the  rate  of  combustion  is  low.  In  the  case 
mentioned  the  rate  was  much  below  that  required  to  work  the 
boiler  to  its  nominal  capacity.  The  effect  is  small  at  the 
higher  rate  and  the  conclusion  may  be  drawn  that  it  is  only 
under  special  conditions  of  work  that  the  matter  is  of  much 
importance. 

The  tests  on  Boiler  No.  10  furnish  a  case  of  economy  pro- 
duced by  automatic  regulation  of  the  draught  over  hand 
regulation.  The  automatic  regulation  secured  an  increased 
evaporation  amounting  to  3.7  per  cent.  The  hand  regulation 
consisted  in  alternately  opening  the  damper  wide  and  changing 


EFFECT  OF    VARIOUS  CONDITIONS   UPON  ECONOMY.     61 

it  to  a  nearly  closed  position,  so  as  to  secure  regular  variations 
of  pressure  over  a  uniform  range.  These  tests  show  the 
tendency  to  loss  produced  by  an  unsteady  draught.  They  do 
not  show,  however,  what  may  happen  in  the  ordinary  work  of 
operating  boilers.  In  the  case  given,  the  firing  was  good  for 
both  methods  of  regulation.  In  ordinary  work  variations 
occur  not  only  in  firing  but  in  other  respects,  and  the  economy 
of  automatic  regulation  may  be  greater  or  even  less  than  that 
obtained  in  the  special  case  cited.  Owing  to  the  important 
part  which  the  personal  element  of  the  fireman  plays  there 
must  be  a  large  difference  in  the  result  produced  in  different 
cases,  and  the  tests  on  some  large  plants,  referred  to  in  the 
memoranda  relating  to  Boiler  No.  10,  one  of  which  gave  a 
result  favoring  automatic  regulation,  and  the  other  favoring 
hand  regulation,  show  this  to  be  true. 

The  use  of  an  artificial  draught,  made  by  a  fan  supplying 
warm  air  to  the  ash  pit  of  Boiler  No.  8,  produced  a  result 
which  was  not  materially  different  from  that  obtained  with  a 
natural  supply  of  unheated  air.  The  fuel  was  a  mixture  of 
anthracite  screenings  and  Cumberland  coal.  There  was  the 
slight  srain  of  2  per  cent,  figured  on  the  weight  of  coal  used, 

O  O  JL  o  C  7 

and  less  than  1  per  cent,  figured  on  combustible. 

The  addition  of  heating  surface  to  Boiler  No.  2,  by  introduc- 
ing pipes  beneath  the  shell  through  which  the  feed- water 
passes  before  it  enters  the  boiler,  seemed  to  increase  the 
evaporation  per  pound  of  coal  3.5  per  cent.  This  gain  does 
not  count  for  much,  because  at  the  time  when  the  pipes  were 
introduced  other  changes  in  the  line  of  improvement  were 
made,  and  this  percentage  simply  represents  the  collective 
result.  It  is  noted  in  these  tests  that  the  temperature  of  the 
escaping  gases  is  low,  being  in  the  first  test  only  355  degrees. 
Little  benefit  can  be  expected  from  an  increase  of  furnace  sur- 
face in  a  case  like  this,  where  there  is  an  indication,  in  the 
small  amount  of  waste  heat,  that  the  heating  surface  already 
provided  absorbs  about  all  the  heat  that  can  be  given  up  to  the 
boiler. 

The  tests  on  Boiler  No.   43   furnish  an  instance  where   the 


62  BOILER   TESTS. 

wetting  of  Cumberland  bituminous  coal  secured  an  apprecia- 
ble advantage.  By  adding  5  per  cent  of  its  weight  of  water, 
the  evaporation,  based  on  the  dry  weight,  was  increased  3  per- 
cent. 

According  to  the  results  of  tests  No.  97  and  No.  98,  the  loss 
produced  by  banking  a  Cumberland  coal  fire  was  about  2  per 
cent. 

The  prevention  of  smoke  was  attained  in  an  almost  complete 
manner  in  Boiler  No.  30,  burning  Cumberland  bituminous 
coal,  by  the  use  of  a  sufficient  quantity  of  air  above  the  fuel 
and  of  superheated  steam  below  the  grate.  The  general 
economic  result  was,  however,  inferior  to  that  obtained  by 
boilers  in  which  the  smoke  is  not  suppressed. 

The  indication  of  the  calorimeter  trials  made  in  connection 
with  the  tests,  so  far  as  they  have  been  conducted,  is  that  the 
steam  produced  by  the  boilers  which  do  not  superheat  is  in 
nearly  a  dry  state.  Horizontal  tubular  boilers  Nos.  2,  9,  32 ? 
35,  36,  39,  42  and  45,  gave  steam  containing  respectively  0.6, 
0.3,  2.2,  0.7,  0.5,  0.2,  0.5  and  0.3  per  cent,  of  moisture,  the 
average  being  0.7  per  cent.  Water-tube  boilers  Nos.  65,  68, 
70fand  71,  gave  respectively  0.6,  1.3,  0.4  and  0.5  per  cent., 
averaging  0.7  per  cent.  The  Galloway  boiler  No.  50  gave  7 
per  cent.,  and  the  single  boiler  which  was  tested  gave  dry 
steam. 

The  remaining  tests  would  be  of  greater  value  if  the  quality 
of  the  steam  had  been  obtained.  It  is  not  unreasonable  to 
apply  the  general  results  of  a  number  of  calorimeter  tests  on 
a  given  type  of  boiler,  to  one  of  the  same  type  where  the 
quality  of  the  steam  is  not  known,  but  it  is  somewhat  unsatis- 
factory when  it  is  seen  that  boilers  of  one  type,  the  horizontal 
type  for  example,  give  percentages  of  moisture  varying  from 
0.2  to  2.2  per  cent.  The  question  naturally  arises  in  a  case 
where  a  high  evaporation  is  produced,  whether  it  is  not  due  in 
a  measure  to  the  wet  quality  of  the  steam.  This  question 
cannot  be  definitely  answered  unless  a  calorimeter  trial  is 
made.  In  the  absence  of  such  a  trial,  however,  there  are  some 
external  evidences  which  throw  light  upon  the  subject.  If  the 


EFFECT  OF   VARIOUS   CONDITIONS   UPON  ECONOMY.      63 

steam  is  wet  and  it  is  used  in  an  engine,  the  observant  engine 
driver  will  be  aware  of  the  fact  by  the  unusual  presence  of 
water  in  the  cylinder.  The  steam  which  escapes  from  the 
indicator  cock,  when  it  is  opened,  will  show  an  excessive 
amount  of  moisture.  The  water  which  is  discharged  by  leak- 
ing flange  joints,  or  by  the  leaking  stuffing  box  of  a  valve  in 
the  steam-pipe,  will  clearly  point  to  wet  steam.  The  moisture 
will  be  seen  at  the  vent  of  the  safety  valve,  if  notice  is  taken 
of  the  escaping  steam  when  the  valve  is  opened.  These  indi- 
cations can  safely  be  credited  when  there  is  more  than  3  per 
cent,  of  moisture.  In  regard  to  the  application  of  this  matter 
to  the  tests  given  in  the  paper,  it  may  be  said  that  there  were 
none  of  these  external  evidences  of  wet  steam  in  any  case 
where  the  calorimeter  trial  was  not  made. 

Little  has  been  said  here  upon  the  subject  of  imperfect  com- 
bustion. It  has  been  incidentally  mentioned  in  the  treatment 
of  boiler  settings,  where  the  effect  of  a  supply  of  air  above 
the  fuel  is  considered.  That  imperfect  combustion  is  a  factor 
in  the  burning  of  bituminous  coal,  the  results,  produced  by  the 
admission  or  exclusion  of  air  clearly  prove.  That  it  is  also  a 
factor  in  the  burning  of  other  kinds  of  coal,  no  one  will 
question.  How  far  it  has  operated  to  affect  the  results  of  the 
various  tests  given,  is  a  matter  about  which  the  reader  must 
form  his  own  opinion.  The  feeling  of  the  writer  is  that  imper- 
fect combustion,  which  doubtless  existed  to  a  greater  or  less 
extent  in  all  cases,  is  not  sufficient  to  change  the  general  con- 
clusions thus  far  set  forth.  It  is  highly  probable  that  a  full 
knowledge  of  the  character  of  the  combustion,  as  determined 
by  analysis  of  the  flue  gases  in  each  case,  would  have  furnished 
a  reason  for  a  few  individual  results,  which,  in  the  light  of  the 
data  at  hand,  appear  somewhat  obscure.  Doubtless,  a  knowl- 
edge of  the  quality  of  the  various  fuels,  obtained  either  by 
chemical  analysis  or  by  determining  the  total  heat  of  combus- 
tion, would  also  have  been  useful  for  the  same  end.  The  deter- 
mination of  these  questions  involves  labor  and  expense  which 
few  care  to  undertake,  and  on  this  account  it  is  outside  the 
province  of  tests  of  limited  scope,  like  those  treated  of  in  the 
paper. 

UNIVBi: 
- 


64  TOILER   TESTS. 

In  conclusion,  it  should  be  stated  that  the  various  boilers 
and  appliances  to  which  the  paper  refers  are  not  designated  by 
their  commercial  names,  and  no  mention  is  made  of  the  local- 
ity where  they  are  in  use.  The  desire  to  give  prominence  to 
principles  rather  than  to  individual  methods  of  carrying  out 
the  principles,  and  to  remove  from  the  discussion  all  matters 
bearing  upon  purposes  of  trade,  has  led  to  this  course.  Fur- 
thermore, it  was  on  condition  that  the  tests  should  be  treated 
in  this  impersonal  way  that  the  interested  parties,  with  a  single 
exception,  granted  permission  for  the  public  use  of  the  results. 
The  exception  is  the  case  of  the  tests  on  boilers  Nos.  64,  65 
66  and  71,  which  are  of  the  Babcock  and  Wilcox  type. 
These  are  given  with  the  permission  of  the  manufacturers 
of  the  boilers,  on  behalf  of  whom  the  tests  were  made. 


PART   II 


(65) 


PART  II. 


Boiler  No.  1. 

(  One  horizontal  return  tubular. 

Llers'    '       ;        '     _'.  I  One  horizontal  direct  tubular. 

Number  used,        .,      .        ..     *...;.'       .    Two. 
Horse-power  (  collective,  basis  12  sq.  ft.),  .    One  hundred  and  seven. 
Kind  of  coal,          .        .       '.        •        •        •    Anthracite, Hazelton, Chestnut. 
Age,        .        .       -*—    ..       .1      .    .     .        .   Fifteen  years. 

Boiler  No.  1  consists  of  two  horizontal  tubular  boilers, 
set  side  by  side,  as  shown  in  the  following  cuts.  They  may 
be  called  superheating  boilers,  since  all  the  steam  generated 
by  them  passes  through  superheating  pipes  located  in  the 
combustion  chamber  under  the  return  tubular  boiler.  The 
direct  tubular  boiler  is  provided  with  steam  heating  surface, 
which  consists  of  the  upper  surface  of  the  shell,  a  part  of 
which  is  exposed  to  the  heat  of  the  escaping  gases.  This 
surface  had  not  been  cleaned  for  a  long  time,  and  probably 
had  little  effect  in  drying  the  steam. 


BOILER  No.  1,  CROSS  SECTION  THROUGH  FURNACES. 


(67) 


BOILER    TESTS. 


BOILER  No.  1  (a),  LONGITUDINAL  SECTION. 


BOILER  No.  1  (6),  LONGITUDINAL  SECTION. 
Dimensions  of  Boiler  No.  1. 


Keturn  Tubular. 

Direct   Tubular. 

Diameter  of  each  shell,      .        .        .in. 

48 

48 

Length  between  heads  and  length  of  tubes, 

ft. 

16 

14 

Number  of  tubes  3  inches  outside  diameter, 

48 

45 

Length  of  combustion  chamber,         .     in. 

- 

38 

Area  of  water-heating  surface,        sq.  ft. 

669 

586 

Area  of  steam-heating  surface,        sq.  ft. 

50 

43 

Area  of  grate  surface,        .         .        sq.  ft. 

19.9 

21.2 

Area  through  tubes,    .        .         .       sq.  ft. 

1.98 

1.86 

Width  of  air  spaces  and    metal    bars  f 

Air  3-8 

Air  3-8 

in  grates,      ....          in.  \ 

Metal  5-8 

Metal  5-8 

Distance  of  grate  to  shell,.        .        .     in. 

18 

17 

Distance  of  bridge  wall  to  shell,         .     in. 

7 

- 

Ratio  of  water-heating  surface  to  grate,  . 

33.  7  to  1 

27.7  to  1 

Ratio  of  grate  to  tube  area, 

10     to  1 

11.  4  to  1 

BOILER   NO.   1. 

Results  of  Tests.     Boiler  No.  1. 


69 


Test  No.  1. 

Test  No.  2. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      lirs. 

10 

9.67 

Coal  consumed  (  including  wood  for  start- 

ing),     .         .        .        .      ...          Ibs. 

3,163 

3,374 

Percentage  of  ash,      ,        .          per  cent. 

15.6 

- 

Water  evaporated,       .         .         .           Ibs. 

26,187 

29,562 

Coal  per  hour,      .     ...        .           Ibs. 

316.3 

349 

Coal  per  hour  per  square  foot  grate,    Ibs. 

7.7 

8.5 

Water  per  hour.  .        .        .        .           Ibs. 

2,618.7 

3,057.1 

Water  per  hour  per  square  foot  water- 

heating  surface,.        .           '  .       Ibs. 

2.09 

2.44 

Horse-power  developed, 

79.4 

92.7 

Boiler  pressure,           .        .                    Ibs. 

73 

71.6 

Temperature  of  feed-water,                 deg. 

200 

200 

Temperature  of  escaping  gases            deg. 

360 

367 

Degrees  of  superheating,   .                   deg. 

66 

None. 

Water  per  pound  of  coal,  .                    Ibs. 

8.28 

8.76 

Water  per  pound  of  coal  from  and  at  212 

degrees,        .....   Ibs. 

8.66 

9.16 

Water  per  pound  of  combustible  from  and 

212  degrees,          .        .        .         .  Ibs. 

10.25 

10.85 

The  object  of  the  tests  on  Boiler  No.  1,  was  principally  to 
determine  the  effect  which  the  use  of  the  superheater  had  upon 
the  economy  of  the  boilers.  Test  No.  1  was  made  with  the 
steam  from  the  two  boilers  passing  through  the  superheating 
pipes,  and  test  No.  2  with  the  superheater  shut  off.  The  steam 
was  superheated  on  test  No.  1  66  degrees,  and  a  comparison 
of  the  two  evaporative  results  shows  that  this  was  attended  by 
a  loss  in  evaporation  of  8.76  —  8.28  =0.48  lb.,  or  5.5  per  cent. 

In  the  same  series  of  tests  to  which  these  belong,  the  effect 
of  placing  an  auxiliary  furnace  beneath  the  superheating  pipes, 
using  coal  at  the  rate  of  4  pounds  per  square  foot  per  hour  on 
a  grate  having  7  square  feet  of  surface,  was  to  secure  a  super- 
heating of  134  degrees,  attended  by  a  reduction  of  9.2  per 
cent,  in  the  evaporative  efficiency.  In  another  experiment  on 
the  same  plant,  a  superheating  of  163  degrees  was  attended  by 
a  reduction  of  10.2  per  cent,  in  the  evaporation  per  pound  of 
total  fuel  used. 

The  same  superheating  pipes,  placed  over  an  independent 
furnace  and  surmounted  by  a  heater  made  of  small  pipes,  pre- 
senting an  aggregate  of  60  square  feet  of  surface,  were  attached 


70  SOIL  EM   TESTS. 

to  a  single  80  horse-power  boiler  of  the  horizontal  tubular  type, 
some  75  feet  distant.  A  test  on  these,  during  which  all  the 
steam  generated  by  the  boiler  passed  through  the  superheater, 
showed  that  473  pounds  of  anthracite  coal  were  required  to 
superheat  23,609  pounds  of  steam  228  degrees.  The  quantity 
of  coal  consumed  in  the  boiler  furnace,  was  2657  pounds,  and 
the  rate  of  combustion  6.3  pounds  per  square  foot  of  grate  per 
hour.  The  rate  of  combustion  in  the  superheater  was  4.8 
pounds  per  square  foot  of  grate  per  hour.  The  evaporation  of 
the  boiler  per  pound  of  combustible  from  and  at  212  degrees, 
was  10.95  pounds;  temperature  of  feed  water,  215  degrees; 
temperature  of  gases,  290  degrees ;  temperature  of  gases 
leaving  superheater,  394  degrees.  In  this  case  a  superheating 
of  228  degrees  required  the  consumption  of  an  additional  17.8 
per  cent,  of  coal  in  the  independent  furnace. 

The  quantity  of  coal  required  for  superheating,  in  all  these 
cases,  is  greater  than  that  which  would  be  expected  if  account 
be  taken  simply  of  the  additional  heat  of  the  steam.  The  dif- 
ference, however,  is  not  more  than  can  fairly  be  attributed  to  a 
slightly  moist  condition  of  the  steam  generated  by  the  boiler 
and  to  loss  of  heat  produced  by  radiation  from  the  pipe  leading 
from,  the  boiler  to  the  superheater,  and  by  radiation  from  the 
superheater  itself. 


Boiler  No.  2. 

Kind  of  boiler,          ......  Horizontal  return  tubular- 
Number  used, Two. 

Horse-power  (  collective,  basis  12  sq.  ft.  ),      .  One  hundred  and  three. 

Kind  of  coal,     .        .        .        .        .        .  Bituminous,  Cumberland. 

Age,    .........  Several  years. 

Boiler  No.  2  consists  of  two  48  inch  boilers,  set  over  a  fur- 
nace common  to  both,  in  the  manner  shown  in  the  following 
cuts.  The  draught  of  the  chimney,  which  is  deficient,  is  aided 
by  a  blower,  which  discharges  the  air  beneath  the  grate. 
Except  in  these  particulars,  the  boiler,  as  arranged  for  the  first 
test,  calls  for  no  special  comment.  The  dotted  lines  shown  in 
the  longitudinal  section  represent  heating  surfaces,  which  were 
introduced  after  the  first  test  was  made.  These  surfaces  con- 


BOILEE  No.   2. 


71 


sisted,  in  part,  of  a  row  of  pipes,  connected  together  with 
return  bends,  placed  behind  the  bridge  wall,  and,  in  part,  of  a 
cylinder,  which  was  located  in  the  place  ordinarily  occupied  by 
the  bridge  wall  at  the  back  end  of  the  grate.  The  total  area 
of  the  surface  thus  introduced  amounted  to  60  square  feet. 
The  feed  water  on  leaving  the  pump  was  first  discharged  into 
the  pipes  and  bridge  wall  cylinder.  After  circulating  through 
these,  it  was  discharged  into  the  steam  space  at  the  top  of  the 
boiler.  At  the  time  of  the  introduction  of  these  pipes,  the 
rear  / \ 


.bridge  wall  at  the 
end  of  the  boiler 
removed  altogether, 
the  opening  above 
wall  at  the  front 
increased, 
also  made  in  the  speed 
of  the  blower,  which,  on 
the  first  test,  was  at  times 
too  low  for  the  desired 


was 
and 
the 
was 


A  change  was 


draught. 


BOILER  No.  2,  CROSS  SECTION  THROUGH  FURNACE. 


BOILER  No.  2,  LONGITUDINAL  SECTION. 


72 


BOILER    TESTS. 


Dimensions  of  Boiler  No.  2. 

Diameter  of  each  shell, 48     in. 

Length  between  heads  and  length  of  tubes,    .         .        .  .  15      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,  .  99 

Area  of  heating  surface,  .        .        ...        .        .  .1,235      sq.  ft. 

Area  of  grate  surface  (  common  to  two  boilers),  .        ,  : .  40.5  sq.  ft. 

Area  through  tubes,  .        .                 .        .        .        .        .  .  4.1  sq.  ft. 

Area  through  flue,      .        .        .        .        .                 .        .  .        2.7  sq.  ft. 

Chimney  height,        .        .        .        .        *        .        .        .  .130      ft. 

Distance  of  grate  to  shell,        .        .        .        «        •      •£.  .  20      in. 

Ratio  of  heating  surface  to  grate,    .        .        .        .        .  .  30.5  to  1 

Ratio  of  grate  to  tube  area,       .        .        .                 .        .  .        9.9  to  1 

Ratio  of  grate  to  flue  area, .  .  15     to  1 

Results  of  Tests.     Boiler  No.  2. 


Test  No.  3. 

Test  No.  4. 

Manner  of  start  and  stop,  .... 

Running. 

Running. 

.Kind  of  run,        .                 .... 

Continuous. 

Continuous. 

Duration,     .                         ...  hrs. 

5.25 

6 

'Coal  consumed,  .                 .        .        .  Ibs. 

2,302 

2,441 

Percentage  of  ash,             .         .  per  cent. 

9.6 

10.5 

Water  evaporated,               .        .        .Ibs. 

19,550 

27,955 

Coal  per  hour      .                 .        .        .Ibs. 

438.5 

406.8 

Coal  per  hour  per  square  foot  of  grate, 

Ibs. 

10.8 

10.0 

"Water  per  hour,  .....   Ibs. 

3,723.8 

3,659.2 

Water  per  hour  per  square  foot  of  heat- 

ing surface,  Ibs. 

3.01 

2.96 

Horse  power  developed,      .        .        H.  P. 

117.3 

115.1 

Boiler  pressure,  Ibs. 

68 

63 

Temperature  of  feed-water,       .        .  deg. 

160 

160 

Temperature  of  escaping  gases,        .  deg. 

355 

346 

Percentage  of  moisture  in  steam,  per  cent. 

0.6 

3.0 

Water  per  pound  of  coal,  .        .        .Ibs. 

8.49 

8.99 

Water  per  pound  of  coal  from  and  at  212 

degrees,         .    .     .        .        .        .Ibs. 

9.22 

9.77 

Water  per  pound  of  combustible  from  and 

at  212  degrees,              ;        .        .  Ibs. 

10.19 

10.91 

The  principal  object  of  the  tests  on  Boiler  No.  2,  was  to 
show  the  effect  produced  by  increasing  the  heating  surface  of 
the  boiler  in  the  manner  noted.  This  object  was  not  fully 
realized,  because  changes  were  made  in  the  setting  of  the 
boilers,  in  addition  to  the  change  in  the  amount  of  heating 
surface.  One  result  produced  was  to  increase  the  percentage 
of  moisture  in  the  steam.  This  was  probably  due  to  the  dis- 
charge of  the  feed  water  into  the  steam  space.  The  increase 


BOILER  No.   3. 


73 


amounted  to  2.4  per  cent.  Making  allowance  for  this  differ- 
ence in  the  quality  of  the  steam,  the  evaporation  was  increased 
on  the  second  test  3.5  per  cent.  Judging  by  the  low  tempera- 
ture of  the  escaping  gases,  the  boiler  absorbed  nearly  the 
whole  of  the  heat  of  the  products  of  combustion,  and  in  this 
respect  the  result  obtained  is  all  that  could  be  desired.  The 
water  evaporated  per  pound  of  combustible  is  less  than  the 
best  results  obtained  from  boilers  of  the  same  type,  using 
Cumberland  coal.  It  is  inferred  from  the  high  proportion  of 
ash,  that  the  coal  was  of  an  inferior  quality,  and  that  this  fact 
had  much  to  do  with  the  low  degree 
of  economy. 


Boiler  No.  3. 


Kind  of  boiler,    .     .     . 

Number  used,  .    ,    \     . 
Horse-power (  collective, 
basis  12  sq.ft.  ), 

Kind  of  coal,  .... 


Horizontal  return 

tubular. 
Six. 

f  Three  hundred 
\  and  thirty-eight, 
f  Anthracite   Lack- 
\  awanna,  broken. 
Age, Six  years. 

Boiler  No.  3  consists  of  a  plant  of 
six  48  inch  boilers,  set  in  one  battery 
of  brick  work,  as  shown  in  the  follow- 
ing cuts.  The  products  of  combustion 
on  leaving  the  tubes  pass  over  the  top 
of  the  shells  to  the  main  flue  at  the 
rear,  and  this  arrangement  provides 
a  small  amount  of  heating  surface 
exposed  to  the  escaping  gases.  There 
is  no  provision  for  cleaning  the  tops  of 
the  shells,  and  this  surface  is  doubt- 
less covered  by  a  deposit  of  soot,  and 
thereby  rendered  inefficient. 


BOILER    TESTS. 


BOILER  No.  3,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  3. 
Diameter  of  each  shell,  .        . 
Length  between  heads  and  length  of  tubes,  . 
Number  of  tubes  (  collective  )  3  inches  outside  diameter, 
Area  of  water-heating  surface,       .        .        .>    .••:••• 
Area  of  steam -heating  surface,       .        .        .        .        .     " 

Area  of  grate  surface,     .        .        .        .        .        . 

Area  through  tubes,        .        .        ,'••', '    .        ...        . 

Area  through  chimney,    .        ,       ....        .  *      . 

Height  of  chimney,          .  dp '  i.  "  :  ..        .        .        . 

Eatio  of  water-heating  surface  to  grate,  •  .  ,  -.  . 
Ratio  of  steam-heating  surface  to  grate,  .  »  . 
Ratio  of  grate  to  tube  area,  .  .  ..  ...  .-  .  . 


48 

15 

288 

4,056 

540 

120 


m. 
ft. 


sq.  ft. 
sq.  ft. 
sq.  ft. 
11.9  sq.  ft. 
11.1  sq.  ft. 
100       ft. 
33.8  to  1 
4.5  to  1 
10.1  to  1 


Results  of  Test.     (  Average  of  three.  )     Boiler  No.  3. 


Manner  of  start  and  stop  and  kind  of  run,    .        .        . 

Duration,          .'..".<:     .       ,.        .        .  '     . 

Coal  fired  (  including  wood  equivalent  ),      .  .        .*  ]    ..,-   • 

Percentage  of  ash  ( including  some  unburned  coal  ),    . 

Water  evaporated,  .        .        .        .       ,.s       .        ;.  ,-:,.- 

Coal  per  hour,  ...       ..  :     * 

Coal  per  hour  per  square  foot  of  grate,          .        ; 

Water  per  hour, 

Water  per  hour  per  square  foot  of  water-heating  surface, 
Horse-power  developed,  ,.      .        .  „      .  -.»?,., 

Boiler  pressure,        .        .  .     .        .\     .        ...      . 
Temperature  of  feed-water,    .        .        . 
Temperature  of  escaping  gases,     .        s 
Water  per  pound  of  coal,        .        .       , . 
Water  per  pound  of  coal  from  and  at  212  degrees, 
Water  per  pound  of  combustible  from  at  212  degrees, 


Test  No.  5 
Ordinary. 


hrs. 
Ibs. 


12 
16,003 

16.7 
136,034 
1,333.6 

11.11 
11,336.1 

2.79 
345 

84.6     Ibs. 

198.6    deg. 

482       deg. 

8.50   Ibs. 

8.96   Ibs. 

10.73   Ibs. 


Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 


The  test  on  Boiler  No.  3  may  be  regarded  as  typical  of  the 
work  done  by  a  large  plant  of  boilers,  using  anthracite  coal, 


BOILER  No.   4. 


75 


which  had  been  in  service  a  number  of  years.  The  ratio  of 
water  heating  surface  to  grate  surface,  which  is  33. 8  to  1,  does 
not  show  what  would  be  called  a  deficiency  of  surface  under 
proper  conditions,  but  in  this  case  the  surface  does  not  appear 
to  have  been  of  sufficient  area  to  absorb  the  whole  heat  of  the 
products  of  combustion.  The  temperature  of  the  gases  was 
482  degrees,  and  this  high  figure,  taken  in  connection  with  the 
fact  of  the  boilers'  age,  is  indicative  of 
the  presence  of  scale  on  the  interior 
surfaces.  The  loss  of  heat  thus  pro- 
duced is  evidently  the  cause  of  the 
somewhat  low  economic  result. 


Boiler  No.  4. 

Kind  of  boiler,       .     Horizontal  rsturn  tubular. 
Number  used,    .     .     Six. 
Horse-power  (col-") 
lective,  basis   12  [-Four  hundred  and  thirty. 


sq.  ft.), 
Kind  of  coal, 


J 


{Mixture   of  Ant h r a c i t e 
Screenings     and     Nova 
Scotia  Culm. 
Age, Two  years. 

Boiler  No.  4  embraces  a  plant  of 
six  horizontal  tubular  boilers,  set  in  one 
battery  of  brick  work,  as  shown  in  the 
following  cuts.  These  boilers  are  ar- 
ranged in  such  a  manner  that  the 
products  of  combustion,  instead  of 
passing  from  the  smoke  arch  at  the 
front  into  the  flue,  in  the  manner 
usually  followed,  are  carried  back  to  the 
rear  of  the  boiler  through  the  two  upper 
rows  of  tubes.  The  number  of  tubes 
in  each  boiler  is  77.  Those  in  the  lower 
rows,  which  carry  the  products  of 
combustion  forward,  number  51,  and 
those  in  the  upper  rows,  referred  to, 
number  26.  The  main  flue  is  located 
at  the  rear  end  and  is  made  of  wrought 
iron.  This  arrangement  of  tubes,  and 


76 


BOILER   TESTS. 


the  use  of  a  fine 
grade  of  coal, 
necessitated  the 
employment  of  a 
blower  to  aid  the 
draught,  the  .  air 
being  discharged 
into  the  ash  pits. 

• 1 1 • • •  The    main    flue 

BOILER  No.  4,  LONGITUDINAL  SECTION.  contains   a  coil   of 

pipe  having  a  total  surface  amounting  to  300  square  feet, 
through  which  the  feed  water  was  passed  before  entering  the 
boiler. 

Dimensions  of  Boiler  No.  4. 

Diameter  of  each  shell,    .     '  .        .        .     . '•;;      "..  .     .        .        60  in. 

Length  between  heads  and  length  of  tubes,  .         .         .         .        15  ft. 
Number  of  tubes  (  collective  )  3  inches  outside  diameter,      .      462 

Area  of  heating  surface,          .        .       ...        .        .        .   6,204  sq.ft. 

Area  of  grate  surface, 150  sq.  ft. 

Area  through  tubes  (  at  smallest  section  ),     ....          6.42  sq.  ft. 

Area  through  chimney,    .         .         ...         .         .         .16  sq.  ft. 

Height  of  chimney, .      120  ft. 

Ratio  of  heating  surface  to  grate  surface,     .        .        .        .       41.4  to  1 

Ratio  of  grate  surface  to  smallest  tube  area,          .         .        .'       23.4  to  1 

Ratio  of  grate  surface  to  chimney  area,          .         .         .         .          9.2  to  1 

Results  of  Tests.     Boiler  No.  4. 

Test  No.  6. 
Manner  of  start  and  stop  and  kind  of  run,    .....   Ordinary. 

Duration, 10.5  hrs. 

Coal  consumed,  moist  (  including  wood  equivalent),     .          11,265  Ibs. 
Proportion  of  bituminous  coal  to  whole,         ....            .178 
Percentage  of  ash  and  waste  coal,           .         .         .         .         .        15.4 

Water  evaporated, 78,849  Ibs. 

Coal  per  hour, 1,072.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,          .        .        .        .         7.15  Ibs. 

Water  per  hour, 7,509.4  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,       .        .          1.21  Ibs. 

Horse-power  developed, 250.3  Ibs. 

Boiler  pressure,        .                                  45  Ibs. 

Temperature  of  feed-water, 89  cleg. 

Temperature  of  escaping  gases, 305  cleg. 

Draught  suction  of  chimney, 3-8  in. 

Drauirht  pressnrs  of  fan 0  to  1-2  in. 

Water  per  pound  of  coal, 7  °°  lbs- 


BOILER  NO.   4. 


77 


Water  per  pound  of  coal  from  and  at  212  degrees,       .        .         8.17       Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,  .         9.66       Ibs. 

The  interest  in  the  test  of  Boiler  No.  4,  centers  in  the 
arrangement  of  tubes  noted,  the  kind  of  fuel  burned,  and  the 
use  of  the  blower  for  increasing  the  draught.  The  only  effect 
of  the  reduced  opening  through  the  tubes,  which  is  noticeable, 
is  the  small  amount  of  power  developed,  this  being  but  little 
over  one-half  of  the  rated  power  of  the  boilers.  The  fuel 
contained  a  large  proportion  of  anthracite  screenings,  which 
produced  a  large  percentage  of  ash.  The  heat  was  well 
absorbed  by  the  boilers,  the  escaping  gases  passing  to  the 
chimney  at  about  the  temperature  of  the  steam.  The  evapora- 
tive result,  considering  the  grade  of  fuel  used,  and  taking 
into  account  the  fact  that  the  fuel  contained  about  4  per  cent, 
of  moisture,  compares  favorably  with  that  obtained  with  the 
best  grades  of  coal. 

The  heat  absorbed  by  the  water  in  passing  through  the  coil 
in  the  flue,  served  to  increase  its  temperature  13  degrees.  The 
water  was  fed  by  an  injector,  the  temperature  of  its  discharge, 
or  approximately  that  of  the  water  entering  the  coil,  being  155 
degrees. 

Subsequent  tests  on  this  boiler,  made  at  intervals  of  about 
a  year,  and  using  different  kinds  of  cheap-grade  anthracite 
coal,  gave  the  following  results  : 


Kind  of  anthracite  coal, 

Screenings. 

Buckwheat. 

Pea  and  Dust. 

Proportion    of    Nova    Scotia 

coal,  ..... 

.14 

.055 

.105 

Percentage  of  ash,     per  cent. 

20 

18 

19.8 

Horse-power  developed,  H.  P. 

380 

368 

561 

Temperature  of  escaping  gas- 

es,     .        .        .         .  deg. 

348 

337 

407 

Water  per  pound  of  coal  from 

and  at  212  degrees,   .    Ibs. 

7.95 

8.92 

8.26 

Water  per  pound  of  combus- 

tible from  and  at  212  de- 

crees,        .         .         .         . 

9.93 

10.87 

10.32 

Draught  pressure  at  blower, 

in. 

•        — 

— 

0  to  1£ 

The  amount  of  power  developed  by  the  boilers  on  the  sup- 
plementary tests  was  increased.  On  the  last  test  the  power 
exceeded  that  of  the  rated  horse  power,  and  it  may  be  noted 


78 


BOILER    TESTS. 


that  this  was  about  the  maximum  which,  under  the  unfavorable 
circumstances  noted,  could  be  obtained.  The  increased 
amount  of  power  obtained  was  accompanied  by  an  increase  in 
the  amount  of  ash,  due  probably  to  a  greater  amount  of  coal 
wasted  by  dropping  through  the  grates.  It  is  seen  that  as  the 
power  increases,  the  temperature  of  the  escaping  gases  becomes 
higher,  reaching  a  maximum  in  the  last  test  of  407  degrees. 
This  is  not  a  high  figure  for  the  amount  of  power  developed? 
and  it  indicates  that  the  special  arrangement  of  tubes  secured 
a  more  thorough  absorption  of  the  heat  than  would  otherwise 
occur. 

Boiler  No.  5. 

Kind  of  boiler,     ?s.w-  ;'*•.       '.        «      :•   .:.••        Horizontal  return  tubular. 
Number  used,  .  ,,   ,.,.  ;,..,v..:.s  .,,,.*  .     .  ;/    ..       One. 
Horse-power,  (basis  12  square  feet),     f    ;    .        Fifty-four. 
Age,          .    •"    .        •  !    •'»••      •        •     '.''••        •        Several  years. 

Boiler  No.  5  is  a  horizontal 
return  tubular  boiler,  set  in 
brick-work  in  the  manner  shown 
in  the  following  cuts.  It  is  the 
end  boiler  of  a  plant  of  the  same 
kind,  and  the  boiler  next  to  it 
was  in  operation  during  the  pro- 
gress of  the  tests.  The  boiler 
is  an  old  one,  and  the  heating 

BOILER  No.  5,  CROSS  SECTION       surfaces   are   somewhat  covered 
THROUGH  FURNACES.  with  scale. 


.,._ 


BOILER  No.  5,  LONGITUDINAL  SECTION. 


BOILER   No.  5. 


79 


Dimensions  of  Boiler  No.  5. 

Diameter  of  each  shell,    .        .        ,        .        ,    .    .        .        .  48 

Length  between  heads  and  length  of  tubes,    .        .        .        .  15 

Number  of  tubes  three  inches  outside  diameter,     ...  49 

Area  of  heating  surface,       "  V  ^'-s  <  i  ^  .  -    .;,     /. .''  ,    *:       .  644 


in. 
ft. 


Area  of  grate  surface,     ,  -••••>>  •«-••'..  .;       .  #{ 
Area  through  tubes,          .        .        .        ,     .   . 
Width  of  air  spaces  and  metal  bars  in  grates, 

Distance  of  grate  to  shell,       ^    *£)    I  -i-:    '•>.  y 
Distance  of  bridge  wall  to  shell,     .  j  :-  .  •'•  .> ..*-.  y  .. 

Ratio  of  heating  surface  to  grate  surface,      .  -i 

Ratio  of  grate  surface  to  tube  area,        .     '  .  i 

Results  of  Tests.     Boiler  No.  5. 


sq.  ft. 
sq.  ft. 
sq.  ft. 
in. 
in. 
in. 
32.2  to  1 
9.9  to  1 


20 
2 

3-8 
27 

8 


Test  No.  7. 

Test  No.  8. 

Test  No.  9. 

Test  No.  10. 

George's 

Delaware 

Mixture  1 

Mixture  1 

Creek,   Cum- 
berland, Bi- 

and Hudson 
Lackawan-  ' 

part  Clunker- 
land,  2  parts 

part   Nova- 
Scotia  Culm, 

tuminous. 

na,  Anthra- 

Pea and 

2  parts  Pea 

cite,  Broken. 

Dust. 

and  Dust. 

Manner  of  start  and  stop 

and  kind  of  run, 

Ordinary. 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,          .         •  hrs. 

11.2 

11.2 

11.2 

'     11.2 

Coal  consumed,  dry   (  in- 

cluding wood  equiva- 

lent),        .        .  Ibs. 

2,277 

2,266 

1,878 

2,080 

Percentage  of  ash, 

per  cent. 

11.1 

14.2 

21.3 

26.2 

Water  evaporated,    .  Ibs. 

20,404 

18,385 

13,144 

13,230 

Coal  per  hour,  .        .  Ibs. 

202.4 

201.4 

167 

184.9 

Coal  per  hour  per  square 

foot  of  grate,    .   Ibs. 

10.1 

10.1 

8.3 

9.2 

Water  per  hour,        .   Ibs. 

1,819 

1,634.3 

1,168.4 

1.176.1 

Water  per  hour  per  square 

foot  of  heating  sur- 

face, Ibs. 

2.8 

2.5 

1.8 

1.8 

Horse-power     developed, 

H.  P. 

60 

53.9 

38.5 

38.8 

Boiler  pressure,        .  Ibs. 

69.4 

69.4 

71.7 

71.6 

Temperature  of  feed-wa- 

•   . 

ter,     .        .         .  deg. 

119.4 

120.5 

119.7 

120.4 

Temperature  of  escaping 

gases,         .        .  deg. 

435 

443 

430 

406 

Number  of  firings,  . 

17 

12 

14 

15 

Number  of  times  slicing 

bar  was  used,     . 

15 

4 

8 

-  18 

Water  per  pound  of  coal, 

Ibs. 

9.08 

8.20 

7.10 

6.46 

Water  per  pound  of  coal 

from  and  at  212  de- 

grees,        .        .Ibs. 

10.25 

9.24 

7.99 

7.27 

Water  per  pound  of  com- 

bustible from  and  at 

212  degrees,        .   Ibs. 

11.52 

10.76 

10.18 

9.87 

NOTE.  —  The  mixed  fuels  were  wet  before  firing  with  5  per  cent,  of  their  weight  of 
water. 


80  BOILER    TESTS. 

The  tests  on  Boiler  No.  5  were  made  to  determine  the  rela- 
tive economy  between  several  different  kinds  of  coal.  The 
Cumberland  coal  gave  the  highest  evaporative  result  and  the 
mixed  coal  the  lowest.  The  evaporation  per  pound  of  Cum- 
berland coal  was  10  per  cent,  higher  than  that  with  Anthracite 
coal,  28  per  cent,  higher  than  that  with  the  mixture  of  pea  and 
dust  and  Cumberland,  and  41  per  cent,  higher  than  that  with 
the  mixture  of  pea  and  dust  and  Nova  Scotia  culm.  Judging 
by  the  percentages  of  ash,  which  are  all  comparatively  large, 
the  coal  was  in  each  case  of  somewhat  inferior  quality.  This 
is  especially  marked  in  the  Cumberland  coal,  which  gave  11.1 
per  cent,  of  ash,  and  in  both  of  the  mixed  fuels.  The  unfavor- 
able effect  produced  by  the  coating  of  scale  on  the  heating 
surfaces  is  seen  in  the  comparatively  high  temperature  of  the 
escaping  gases. 

An  important  feature  of  the  results  is  the  relative  amount  of 
power  developed  by  the  various  fuels.  The  dampers  were 
kept  wide  open  during  each  test  and  the  boilers  produced  a 
maximum  quantity  of  steam  under  each  condition.  The 
Cumberland  coal  produced  the  largest  amount,  viz.,  60  horse- 
power, and  this  is  22  per  cent  above  the  nominal  capacity. 
Then  comes  the  anthracite  coal  and  finally  the  ^mixed  fuels. 
The  mixed  fuels  produced  22  per  cent  below  the  rated  power 
of  the  boilers.  Another  feature  is  the  labor  involved  in  using 
the  various  fuels,  as  indicated  by  the  number  of  times  the 
slicing-bar  was  employed  in  breaking  up  the  bed  of  coal.  The 
anthracite  coal  gives  the  most  favorable  showing,  while  the 
mixture  of  culm  and  pea  and  dust  gives  the  least  favorable 
showing.  The  difference  in  the  labor  involved  in  slicing  a 
fire  four  times  per  day  and  eighteen  times  per  day  is  con- 
siderable. 

The  actual  economy  obtained  with  the  different  fuels  is  shown 
by  the  following  table,  which  gives  the  cost  of  coal  required  to 
generate  30,000  pounds  of  steam,  according  to  quotations  of 
prices  which  ruled  at  the  time  of  the  tests. 


BOILEE   No.    5. 


81 


Cumberland. 

Anthracite. 

Mixture 
Cumberland 
and  Pea 
and  Dust. 

Mixture 
Culm  and 
Pea 
and  Dust. 

Cost  of  coal  per  ton  of 
2,240  pounds,     . 
Cost    of     coal     required 
to    evaporate    30,000 
pounds      of      water 
from  and  at  212  de- 
grees, 

$5.90 
7.70 

$5.60 
8.11 

$4.47 
7.50 

$3.75 

6.88 

The  extreme  difference  in  these  figures  is  $1.23,  which  cor- 
responds to  15  per  cent.,  and  this  occurs  between  the  anthra- 
cite coal,  which  is  the  most  easily  worked,  and  the  mixed  fuel 
containing  culm,  which  requires  the  most  labor  in  firing.  If 
one  fireman  be  assumed  capable  of  handling  ten  tons  of  anthra- 
cite coal,  broken  size,  per  day,  and  his  wages  are  $2.00  per 
day,  the  cost  of  fireman's  labor  represents  3.6  per  cent,  of  the 
cost  of  fuel.  A  saving  of  15  per  cent,  in  the  cost  of  fuel, 
when  using  10  tons  per  day  of  the  mixture  named,  is  sufficient 
to  cover  the  increased  cost  of  labor  due  to  the  employment  of 
another  fireman,  and  still  have  11.4  per  cent,  remaining  for  a 
net  saving. 

Additional  tests  were  made  on  Boiler  No.  5,  using  Franklin 
and  Kalmia  coal,  each  of  which  was  quoted  at  $6.75  per  ton. 
The  Franklin  coal  gave  an  evaporation  of  9.78  pounds  of  water 
from  and  at  212  degrees  per  pound  of  coal,  and  the  Kalmia 
coal,  9.68  pounds.  The  percentage  of  ash  in  each  of  these 
coals  was  10.8  per  cent.,  while  in  the  Lackawanna,  on  Test  No. 
8  the  percentage  was  14.2.  It  is  evident  that  the  improved 
performance  with  these  coals  was  due  simply  to  the  greater 
proportion  of  combustible  matter  which  the  coal  contained. 

Boiler  No.  6. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used, One. 

Horse-power  (  basis  12  square  feet ),         .     Sixty-three. 

Kind  of  coal,  f  Mixture  two -parts  Screenings, 

'  1     one  part  Nova  Scotia  Culm. 
Ag?, Several  years. 


BOILER    TESTS. 


Boiler  No.  6  is  a  horizontal 
tubular  boiler,  set  in  brick- work 
in  the  manner  shown  in  the  fol- 
lowing cuts.  It  is  located  at  the 
end  of  a  battery  of  boilers  of  the 
same  kind,  and  during  the  pro- 
gress of  the  tests  all  the  boilers 
were  in  operation.  The  arrange- 
ment of  the  setting  is  such  that 
air  is  admitted  over  the  fire  in  a 
finely  divided  state.  For  this 
purpose  perforated  plates  are  in- 
troduced in  the  side  walls  of  the  furnace  and  in  the  top  of  the 
bridge  wall,  and  the  air  is  supplied  through  these  plates  from 
ducts  extending  back  and  forth  through  the  walls. 


BOILER  No.  6,  CROSS  SECTION 
THROUGH  FURNACE. 


BOILER  No.  6,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  6. 
Diameter  of  shell,  .       >•"     .'..„..   [  .  .        .        . 

Length  between  heads  and  length  of  tubes,  . 
Number  of  tubes  3  inches  outside  diameter,      .    .        . 
Area  of  heating  surface,        .        .        .        .£      .        . 

Area  of  grate  surface,    .        .        .        ...        '. 

Area  through  tubes,        -.',.      .        .        .     •   .    .    '.  ..*••• 

Width  of  air  spaces  and  metal  bars  in  grates, 
Distance  of  grate  to  shell,      .        .        .        .        •  j      • 

Distance  of  bridge  wall  to  shell,    ..... 

Ritio  of  heating  surface  to  grate  surface, 

Ratio  of  grate  surface  to  tube  area,       .... 


in. 

ft. 


54 

15 

GO 

757  sq.  ft. 

22.5  sq.  ft. 

2  5  sq.  ft. 

3-8  in. 

27  in. 

8  in. 
33.7  to  1 

9  to  1 


BOILEE  No:  ft 

Results  of  Tests.     (Average  of  two  clays.  )     Boiler  No.    6. 


83 


Test  No.  11. 

Test  No.  12. 

Conditions  regarding  air  passages,     .        .      | 

Air  passages 
open. 

Air  passages 
closed. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,     hrs. 

11.4 

10.8 

Coal  consumed,  dry  (  including  wood  equiva- 

lent),       Ibs. 

2,820 

2,673 

Percentage  of  ash,      ....  per  cent. 

14.3 

16.1 

Water  evaporated,       .....   Ibs. 

17,828 

16,557 

Coal  per  hour,      Ibs. 

297.9 

248.7 

Coal  per  hour  per  square  foot  of  grate,     .  Ibs. 

11.02 

11  05 

Water  per  hour,           .        .        .        .         .Ibs. 

1,567.7 

1,541.3 

Water  per  hour  per   square  foot  of  heating 

surface,         .         .         .        ...  Ibs. 

2.06 

2.03 

Horse-power  developed,     .        .        .         H.  P. 

53.7 

52.8 

Boiler  pressure,  .         .        ....      .Ibs. 

68.9 

68.7 

Temperature  of  feed-water,       .        .        .  cleg. 

72.2 

71.6 

Temperature  of  escaping  gases,        .        .  cleg. 

453 

461 

Draught  suction,         .         .         .         .         .in. 

0.36 

0.36 

Water  per  pound  of  coal,  .         .         .        .Ibs. 

6.32 

6.19 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,   .......  Ibs. 

7.44 

7.30 

Water  per  pound  of  combustible  from  and  at 

212  degrees,          .....  Ibs. 

8.69 

8.69 

NOTE.  —  The  coal  when  fired  contained  5  per  cent,  of  its  weight  of  water. 

The  object  of  the  tests  on  Boiler  No.  6  was  to  determine  the 
effect  of  excluding  the  air  from  the  ducts  in  the  walls,  when 
burning  a  mixture  of  anthracite  screenings  and  Nova  Scotia 
culm.  One  test  was  made  with  the  passages  open  in  the 
ordinary  manner,  and  another  with  the  entrance  to  the  ducts 
closed.  During  the  first  test  the  air  registers,  with  which  the 
fire  doors  were  provided,  were  closed,  and  during  the  second 
test  the  registers  were  open  a  part  of  the  time.  The  compara- 
tive tests  are  thus  made  between  two  systems  of  introducing 
air  above  the  fuel,  one  the  special  method  for  which  the  boiler 
was  set,  and  the  other  the  common  method  of  introducing  it 
through  the  fire  door.  The  evaporative  results  of  these  tests, 
which  are  an  average  of  two  days'  run  in  each  case,  do  not 
show  a  material  difference.  Basing  the  results  on  the  evapor- 
ation per  pound  of  coal ,  there  appears  to  be  a  loss  of  about  2 
per  cent  in  closing  the  air  ducts  and  using  the  air  registers  in 
the  fire  door.  Basing  the  results  on  the  evaporation  per 


84  BOILER    TESTS. 

pound  of  combustible,  there  is  an  exact  agreement  between  the 
two. 

The  results  of  this  comparison  show  that  the  manner  in 
which  the  gaseous  products  of  the  furnace  appear  to  be  con- 
sumed, as  viewed  by  the  eye  of  an  observer,  does  not  necessa- 
rily indicate  much  as  to  the  true  economy  with  which  the 
combustion  takes  place.  As  thus  viewed  there  was  a  marked 
improvement  in  the  character  of  the  combustion  when  the  air 
passages  were  open,  over  the  appearance  when  they  were 
closed. 

The  boilers  developed  less  than  their  rated  capacity,  even 
with  a  constant  draught  of  3-8  of  an  inch  water  pressure, 
which  is  the  full  draught  of  a  100  ft.  chimney.  The  evapora- 
tion per  pound  of  coal  in  both  tests  was  much  below  that 
obtained  with  the  best  grades  of  coal.  This  is  not  surprising 
in  view  of  the  nature  of  the  fuel,  which  is  liable  to  be  of 
inferior  quality. 

Boiler  No.  7. 

Kind  of  boiler,     .         .        .        .    .    .        .     Horizontal  return  tubular. 

Number  used,       .        .        .    '    i.       .        .    Six. 

Horse-power  (  collective,  basis  12  sq.  ft.  )      Four  hundred  and  seventy. 

(  Anthracite  Screenings  3  parts, 
'  \  Cumberland  bituminous  1  part. 
Age,      .         .        .         .         .        .         .         .     Five  months. 

Boiler  No.  7  embraces  a  plant  of  six  horizontal  return 
tubular  boilers,  set  in  one  battery  of  brick  work.  The  style 
of  setting  is  that  shown  in  the  cut  of  Boiler  No.  6.  Air  is 
supplied  above  the  fuel  through  perforations  in  the  side  walls 
and  bridge  wall,  in  the  same  manner  as  in  that  boiler.  The 
air  ducts  in  this  case  are  supplied  through  sheet  iron  pipes, 
which  are  placed  in  the  flue.  These  present  about  3  per  cent, 
as  much  surface  to  the  heat  of  the  gases  as  the  area  of  the 
heating  surface  in  the  boilers.  The  air  supplied  above  the 
fuel  is  thus  made  to  utilize  some  of  the  heat  which  would 
otherwise  be  wasted. 


BOILER  No.    7.  85 

Dimensions  of  Boiler  No.    7. 

Diameter  of  each  shell,      .        .        .     ,  .,      -..'...        .,  '         GO  in. 

Length  between  heads  and  length  of  tubes,      *         .         .  15  ft. 

Number  of  tubes  (collective;  31-2  inches  outside  diameter,     348 

Area  of  heating  surface,    .        .         .         ...       ..        .  5,646  sq.  ft. 

Area  of  grate  surface,        -       •        .        .        .        .        .  150  sq.ft. 

Area  through  tubes,    .        .        .-       .         .         .         .    .'    .  20  sq.  ft. 

Height  of  chimney,    .        .        .        .        .        -        '        •  150  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  .        ..        .  3-8  in. 

Katio  of  heating  surface  to  grate  surface,        .        .        .  37.6  to  1 

Ratio  of  grate  surface  to  tube  area, .        .        .....  7.5  to  1 

Eesults  of  Tests.     (  Two  days.  )     Boiler  No.  7. 

Test  No.  13. 

Manner  of  start  and  stop  and  kind  of  run,  .        .        .         Ordinary. 

Duration,    .        .        .        ;/     .        ||      -        •        •        •  13-5          hrs. 

Coal  consumed,  dry  ( including  wood  equivalent ),  .         .     20,476  Ibs. 

Percentage  of  ash,     .        .        .        .        .        ...        *  14. 2  percent. 

Water  evaporated,      .        .        .        .        .   '     .        .      '.  163,705  Ibs. 

Coal  per  hour,     .        .        .        .        .        .        .        •        .      1,516.7          Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .  10.1  Ibs. 

Water  per  hour, ...     12,125.9          Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,         .  2.1          Ibs. 

Horse-power  developed,     .        .        .        .        .      ...         404.2       H.  P. 

Boiler  pressure,  .        .        ..       .        .        .        .  86  Ibs. 

Temperature  of  feed-water,      .        .        .  '     .        .        .          102  deg. 

Temperature  of  escaping  gases,        .        .        .        .        .         410  deg. 

Water  per  pound  of  coal,  .        .        .        .-       .        .        .  7.99        Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,  .        .  9.18        Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,         10.70        Ibs. 
NOTE.  —  The  coal  when  fired  contained  5  per  cent,  of  water. 

The  results  of  the  test  on  Boiler  No.  7  furnish  an  example 
of  the  performance  of  a  low  grade  of  fuel  in  a  large  plant  of 
new  boilers,  where  the  conditions  were  favorable  for  obtaining 
a  good  result.  The  evaporation  per  pound  of  coal  compares 
favorably  with  that  produced  in  many  cases  with  the  best 
grades  of  anthracite  coal,  and  this  is  all  that  could  be  desired 
from  fuel  composed  largely  of  screenings.  In  this  case  the 
screenings  were  evidently  of  good  quality. 


86 


BOILEE    TESTS. 
Boiler  No.  8. 


Kind  of  boiler,  .        .        .        . 

Number  used,     .        .    '    .        .        . 
Horse  power  (basis  12  square  feet  ), 

Kind  of  coal,      .        .        .     .  -  . 
Age,    .        .        .        I   .    .        .    .    . 


.     Horizontal  tubular. 

.     One. 

.     One  hundred. 

f  Anthracite  pea  and  dust  3  parts, 
.  \      George's  Creek  Cumberland  1 

[     part. 
.     New. 


Boiler  No.  8  is  a  horizontal  tubular  boiler,  provided  with  a 
detached  furnace,  and  the  general  features  of  the  boiler  and 
setting  are  shown  in  longitudinal  section  in  the  following  cut. 
The  furnace  has  the  same  location  with  respect  to  the  tubes  as 
that  found  in  the  locomotive  type  of  boiler.  The  products  of 
combustion  pass  forward  through  the  tubes,  and  after  return- 
ing beneath  the  shell,  they  enter  the  chimney  from  the  front 
end.  The  boiler  is  provided  with  forced  draught,  which  is 
supplied  by  a  blower  discharging  air  under  the  grates.  The 
air  from  the  blower  first  passes  through  a  pipe  in  the  flue 
space  beneath  the  shell,  which  presents  a  heating  surface 
amounting  to  15  per  cent  of  the  area  of  that  in  the  boiler. 
The  temperature  of  the  air  supplied  under  the  grates  when  the 
blower  was  in  operation,  was  increased  by  this  means  about  40 
degrees. 


BOILER  No.  8,  LONGITUDINAL  SECTION. 


BOILEE   No.    8. 


87 


Dimensions  of  Boiler  No.  8. 

Diameter  of  shell,      .        .        >*      ...->;.        .     ->.      .  .  72      in. 

Length  between  heads  and  length  of  tubes,     .        .'    \  .  .  15      ft. 

Number  of  tubes  4  inches  outside  diameter,    .        ;.         .  .  70 

Area  of  heating  surface,  .        .        .        .   ...        .  .  1,189      sq.ft. 

Area  of  grate  surface,       .         .         .         ......       •         •  •  36      sq.  ft. 

Area  through  tubes,  ....         .         .         .    -     .  .  5.3  sq.  ft. 

Area  through  chimney,       .        .         .    '  .  .         .  "v  -4        .  .  5.9  sq.  ft. 

Height  of  chimney,   .        .                 .     "  .        .        ....  GO      ft. 

Width  of  air  spaces  ana  metal  bars  in  grates,          Air  7-16  in.,  metal  3-8  in. 

Ratio  of  heating  surface  to  grate  surface,       .        .        .  . .  33     to  1 

Ratio  of  grate  surface  to  tube  area,         ...        .  .  6.7  to  1 

Results  of  Tests.     Boiler  No.  S. 


Test  No.  14. 

Test  No.  15. 

Natural  draft. 
Ordinary  with 
preliminary 
heating- 
Continuous. 
7.2 

2,750 
11 
21,876 
379.4 
10.5 
3,017.4 

2.5 
105.6 
70 
51 
395 
7.95 

9.54 
10.73 

Forced   draft. 
Ordinary  with 
preliminary 
heating. 
Continuous. 
7.5 

3,430 
9.6 
27,869 
457.4 
12.7 
3,715.9 

3.1 
130 
71 
52 
400 
8.12 

9.74 
10.79 

Manner  of  start  and  stop.      .       ...                \ 

Kind  of  run,  .        .  "     .        ... 
Duration,         .        .         .         .        „•'.'       .  hrs. 
Coal  consumed,  dry  (including  wood  equiv- 
alent),         Ibs. 
Percentage  of  ash,         .        .        .  per  cent. 
Water  evaporated,          .       •.        .        .  Ibs. 
Coal  per  hour,        .        .        .        .        .  Ihs. 

Coal  per  hour  per  square  foot  of 
Water  per  hour, 
Water  per  hour  per  square  foot 
surface,     .... 
Horse-power  developed, 

grate,   Ibs. 
.  Ibs. 
of  heating 
.   Ibs. 
H.  P. 
.    Ibs. 

Temperature  of  feed-water,.        *        .  deg. 
Temperature  of  escaping  gases,    .         .  deg. 
Water  per  pound  of  coal,       .        .         .Ibs. 
Water   per  pound  of  coal  from  and  at  212 
degrees,     Ibs. 
Water  per  pound  of  combustible  from  and 

NOTE.  —  The  coal  was  wet  before  firing,  and  the  weight  was  increased  by  this  means 
about  6  per  cent. 

The  tests  on  Boiler  No.  8  were  made  to  determine  the  com- 
parative economy  of  forced  draught  with  heated  air,  and  natural 
draught,  where  the  fuel  was  largely  composed  of  anthracite 
screenings,  together  with  the  general  result  produced  by  the 
use  of  a  detached  furnace.  An  exact  comparison  cannot  be 
made  between  the  two  tests,  owing  to  the  different  conditions 
in  respect  to  capacity,  130  horse-power  being  developed  with 


88  BOILER   TESTS. 

forced  draught,  and  105.6  horse-power  with  natural  draught. 
Taking  the  results,  however,  as  they  stand,  there  is  a  gain 
amounting  to  2  per  cent,  in  favor  of  forced  draught,  figured  on 
coal,  and  0.5  per  cent,  figured  on  combustible.  The  small 
advantage  produced  by  the  forced  draught  may  be  attributed 
wholly  to  the  heated  air -which  was  used.  It  is  to  be  borne  in 
mind  that  with  forced  draught  there  is  a  chance  for  loss  from 
excessive  supply  of  air  at  times  when  the  bed  of  coal  is  allowed 
to  burn  through  to  the  grate.  The  loss  from  this  source  is 
liable  to  be  greater  with  forced  draught  than  with  natural 
draught,  on  account  of  the  greater  quantity  and  force  of  the 
air  supplied  by  the  blower.  Little,  if  any  benefit,  for  this 
reason,  can  be  expected  under  ordinary  conditions  of  firing 
from  a  forced  draught,  and  the  results  of  the  tests  bear  out 
these  expectations. 

The  evaporative  results,  taken  by  themselves,  show  a  favor- 
able performance  of  the  boiler,  for  the  class  of  fuel  that  was 
used.  Compared  with  the  results  obtained  from  boilers  set  in 
the  ordinary  way,  with  the  fire  box  beneath  the  shell,  the 
figures  do  not  show  any  special  improvement,  and  the  conclu- 
sion may  be  drawn  that  the  use  of  a  detached  furnace  is  not 
especially  advantageous.  In  this  form  of  furnace  the  fire 
is  surrounded  by  highly  heated  brick  work,  which  keeps 
the  furnace  at  a  high  temperature.  In  the  ordinary  setting  the 
temperature  is  much  reduced  by  the  close  proximity  of  the 
heating  surfaces  of  the  boiler  to  the  furnace.  The  use  of  a 

o 

detached  furnace,  on  account  of  the  higher  temperature,  would 
be  expected  to  secure  the  best  result.  The  same  cause,  how- 
ever, which  produces  the  high  temperature,  leads  to  a  consid- 
erable amount  of  loss  of  heat,  on  account  of  radiation  from  the 
top  and  sides  of  the  furnace,  and  this  stands  in  the  way  of 
realizing  the  whole  benefit,  which  would  otherwise  be  expected 
from  this  system. 

Another  test  was  made  on  Boiler  No.  8,  using  screenings 
alone  with  forced  draught  ( the  screenings  being  wet  7  per 
cent,  before  firing  ) .  The  percentage  of  ash  was  15  per  cent.  ; 
the  horse-power  developed  was  the  same  as  in  test  No.  14  ;  the 


BOILER  No.    9. 


89 


temperature  of  the  escaping  gases  was  356  degrees  (39  degree,0 
lower  than  that  of  test  No.  14  ) .  The  evaporation  from  and  at 
212  degrees  was  8.17  pounds  per  pound  of  coal  and  9.63 
pounds  per  pound  of  combustible.  It  is  not  certain  that  the 
screenings  here  used  was  of  the  same  quality  ( though  of  the 
same  name)  as  those  used  in  the  mixture  tests  ;  nevertheless, 
a  large  gain  appears  to  have  been  produced  by  the  introduction 
of  25  per  cent,  of  Cumberland  coal.  The  increase,  figured 
upon  combustible,  is  about  11  per  cent. 


Boiler  No.  9. 

Kind  of  boiler,          ..        ...        .        ..' 

Number  used,  .        .v       .        .        .        .        . 

Horse-power  (basis  12  square  feet  ),      .        . 
Age,    '•".....        .        .        .    /,:.  ."  . 


Horizontal  return  tubular. 

One. 

Seventy-four. 

Two  months. 


Boiler  No.  9  is  of  the  horizontal  tubular  type,  though  unlike 
the  ordinary  form  in  being  provided  with  a  water  leg,  which 
forms  the  front  wall  of  the  furnace.  The  arrangement  of  the 
water  leg,  and  the  general  features  of  the  boiler,  together  with 
the  manner  in  which  it  is  set,  are  shown  in  the  following  cuts. 
The  water  leg  extends  a  short  distance  below  the  level  of  the 
grates,  and  at  the  proper  point  it  is  provided  with  an  opening 
through  which  the  coal  is  fired.  The  setting  is  so  arranged,  as 
shown,  that  air  is  supplied  to  the  products  of  combustion  as 
they  pass  the  bridge  wall.  The  air  is  introduced  through  a 
pipe  laid  inside  the  brick  work,  and  distributed  to  cast  iron 
globes,  which  rest  upon  the 
top  of  the  bridge  wall. 
The  surfaces  of  these  globes 
are  perforated.  A  jet  of 
steam  is  introduced  into  the 
end  of  the  supply  pipe,  and 
a  mixed  current  of  air  and 
steam  is  thereby  distributed 
through  the  burning  gases. 
The  size  of  the  steam  pipe 
is  3-8  of  an  inch,  and  its 


outlet  is  drawn  down  to  a 


BOILER  No.  9,  CROSS  SECTION  THROUGH 
FURNACE. 


90 


BOILEE    TESTS. 


diameter  of  about  1-4  of  an  inch.  The  air  which  is  fed  to 
the  bridge  wall  pipe  first  passes  through  the  air  spaces  in  the 
side  walls  of  the  setting,  by  which  means  it  is  somewhat  heated. 


BOILER  No.  9,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  No.  9. 

Diameter  of  each  shell, GO      in. 

Length  between  heads  and  length  of  tubes,     .         .         .         .  15      ft. 

Number  of  tubes  3  inches  outside  diameter,  GG 

Area  of  heating  surface,   ........  890      sq.  ft. 

Area  of  grate  surface, 25.7  sq.  ft. 

Area  through  tubes, .2.7  sq.ft. 

Area  through  chimney, -,        ,         7      sq.  ft. 

Height  of  chimney,  .         .         .         .         .         .         .  •    ... '      •'.  90      ft. 

Width  of  air  spaces  and  metal  bars  in  grate,  .         .  Air  3-8  in.,  metal  1-2  in. 

Distance  of  grate  to  shell,         .         ...         .        .. '      .  26      in. 

Distance  of  flat  bridge  wall  to  shell,        .        .     .»        .        .         9      in. 

Ratio  of  heating  surface  to  grate  surface,       .     '  .        .        .  34. G  to  1 

Ratio  of  grate  surf  ace  to  tube  area, 9.4  to  1 


BOILER  No.   9. 
Results  of  Tests.     Boiler  No.  9. 


91 


Test  No.  16. 

Test  No.  17. 

Test  No.  18. 

r 

George's 

Equal  parts 

Kind  of  coal,         .        .        .      \ 

Creek,  Cum- 
berland, Bitu- 

Lehigh Egg, 
Anthracite. 

Anthracite. 
Screenings,   & 

( 

minous. 

Cumberland. 

Manner  of    start  and  stop  and 

kind  of  run,  .... 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,      ....  hrs. 

14 

17.5 

14.5 

Coal  consumed,  dry    (including 

wood  equivalent),         .   Ibs. 

6,559 

6,309 

5,102 

Percentage  of  ash,       .  per  cent. 

6.6 

9.4 

13.5 

Watar  evaporated,        .        .Ibs. 

56,555 

53,153 

39,658 

Coal  per  hour,       .        .        .Ibs. 

498.5 

360.5 

351.5 

Coal  per  hour  per  square  foot  of 

grate,      .        .        .        .Ibs. 

18.2 

14 

13.7 

Water  per  hour,   .        .        .  Ibs. 

4,039.7 

3,037.3 

2,735.1 

Water  per  hour  per  square  foot 

of  heating  surface,        .   Ibs. 

4.5 

3.4 

3.1 

Horse-power  developed,       H.  P. 

143.8 

105.5 

95.1 

Boiler  pressure,    .         .        .Ibs. 

66 

62 

65 

Temperature  of  feed-water,  deg. 

40 

40 

42 

Temperature  of  escaping  gases, 

deg. 

40.3 

349 

343 

Percentage  of  moisture  in  steam, 

0.3 

per  cent. 

_ 

- 

Water  per  pound  of  coal,     .   Ibs. 

8.62 

8.42 

7.77 

Water  per  pound  of  coal  from 

and  at  212  degrees,        .   Ibs. 

10.43 

10.18 

9.39 

Water  per  pound  of  combustible 

from  and  at  212  degrees,  Ibs. 

11.17 

11.24 

10.85 

The  tests  on  Boiler  No.  9  were  made  to  determine  the  rela- 
tive economy  and  capacity  of  this  type  of  boiler  with  different 
kinds  of  fuel.  The  results  of  the  tests  are  chiefly  interesting 
in  showing  the  quantity  of  power  which  can  be  obtained  from 
a  boiler  of  the  horizontal  return  tubular  type  under  the  differ- 
ent conditions  of  the  tests.  The  chimney  gave  a  draught 
corresponding  to  three-eights  of  an  inch  water  pressure,  and 
the  damper  was  carried  wide  open  on  all  the  tests,  so  as  to 
secure  its  full  capacity.  Moreover,  the  fires  were  well  tended 
so  that  they  should  do  their  maximum  work,  being  frequently 
broken  up  and  sliced,  not  only  when  the  bituminous  coals  were 
burned,  but  also  when  anthracite  coal  was  burned.  Under 
these  conditions  the  developed  power,  when  Cumberland  coal 
was  used ,  was  nearly  two  times  the  rated  power ;  when 
anthracite  Lehigh  was  used  it  was  nearly  50  per  cent,  larger, 


92  BOILER    TESTS. 

and  when  the  mixture  of  equal  parts  of  screenings  and  Cum- 
berland coal  was  burned,  it  was  nearly  one-third  larger.  Com- 
pared among  themselves  the  Cumberland  coal  developed  36 
per  cent,  more  power  than  the  anthracite  coal  and  50  per  cent, 
more  power  than  the  mixture. 

The  relative  economy  of  these  fuels  is  not  fairly  shown 
because  of  the  large  difference  in  the  conditions  as  to  capacity, 
especially  in  the  case  of  the  test  of  the  Cumberland  coal.  The 
low  result  produced  here  is  no  doubt  due  to  the  loss  attending 
the  large  capacity,  this  being  shown  in  the  comparatively  high 
temperature  of  the  escaping  gases.  Considering  the  large 
amount  of  power  developed  in  the  case  of  the  test  with  anthra- 
cite coal,  the  result  in  this  case  shows  a  high  degree  of 
economy.  The  high  rate  of  combustion,  viz.,  14  pounds  per 
square  foot  of  grate  per  hour,  and  the  low  temperature  of  the 
escaping  gases,  which  was  349  degrees,  are  the  two  vital  ele- 
ments which  contributed  to  this  result. 

A  subsequent  test  was  made  to  determine  the  effect  produced 
upon  the  economy  of  the  boiler  by  dispensing  with  the  admis- 
sion of  air  at  the  bridge  wall.  The  test  was  made  when 
using  Cumberland  coal,  and  the  principal  results  obtained  were 
as  follows  :  — 

Coal  per  hour  per  square  foot  of  grate,  .  .  .  .  18.8  Ibs. 
Percentage  of  ash,  ........  7  per  cent. 

Horse-power  developed, 135  H.  P. 

Temperature  of  feed-water,      .        .        .        ...  40  deg. 

Temperature  of  escaping  gases,        .        .        .        ...  486  deg. 

Water  per  pound  of  coal,         '.        .        .        .        *        .           7.94  Ibs. 

Water  per  pound  of  coal  from  and  at  212  d3gr33S,          ,           9.62  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  10.34  Ibs. 

Comparing  the  results  of  this  test  with  those  of  test  No.  16, 
made  with  air  in  use,  it  appears  that  the  evaporation  per  pound 
of  coal  was  reduced  nearly  8  per  cent. 

Boiler  No.  1O. 

Kind  of  boiler,       .        .        .        .  '  -  .  .  Horizontal  return  tubular. 

Number  used,        •.;      ''.        .        ...  .  One. 

Horse-power  (basis  12  square  feet  ),    .  .  Fifty-five. 

Kind  of  coal,          .        .        v        .        .  .  Anthracite  Lehigh,  broken. 

Age,         .        .        .        ....  .  Several  years. 


BOILER   No.   10. 


93 


Boiler  No.  10  is  of  the  ordinary  horizontal  tubular  type. 
The  manner  in  which  it  is  set  is  shown  in  the  following  cut, 
which  is  a  longitudinal  section.  The  top  of  the  bridge  wall  is 
curved  upward,  so  as  to  conform  to  the  curve  of  the  shell,  and 
the  space  behind  is  filled  and  curved  at  the  top  in  a  similar 
manner.  The  products  of  combustion  on  leaving  the  smoke 
arch  in  front,  pass  through  the  flue  space,  over  the  top  of  the 
shell,  and  thence  to  the  chimney.  The  manner  in  which  this 
is  arranged  is  similar  to  that  shown  in  the  cross  section  given 
in  connection  with  Boiler  No.  3.  This  arrangement  secures  a 
small  amount  of  steam  heating  surface,  though  the  position  of 
this  surface  is  such  as  to  be  more  or  less  inefficient,  on  account 
of  deposits  of  soot. 


BOILER  No.  10,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  10. 

Diameter  of  each  shell, 

Length  between  heads  and  length  of  tubes, 
Number  of  tubes  3  inches  outsid2  diameter,    . 

Area  of  water-heating  surface, 

Area  of  steam-heating  surface,        ..... 

Area  of  grate  surface, 

Area  through  tubes,  .        .        .        .        .        .        *       '  • 

Width  of  air  spaces  and  metal  bars  in  grates,          .        . 
Distance  of  grate  to  shell,        .        .        .'  •- ".      '.        .' 
Distance  of  curved  bridge  wall  to  shell,  . 
Katio  of  water-heating  surface  to  grate  surface,     ... 
Katio  of  steam-heating  surface  to  grate  surface,     .  • '     . 
Ratio  of  grate  to  tube  area,      .        .        *     /•  * 


48 

16 

48 

656 

80 


in. 

ft. 

sq. 
sq. 


19.5  sq 

2     sq 

3-8     in. 

24     in. 
8     in. 

33.5  to  1 
4.1  to  1 
9.7  to  1 


94 


n OILER    TESTS. 
Results  of  Tests,  Boiler  N~a.  10. 


Test  No.  19. 

Test  No.  20. 

Test  No.  21. 

Test  No.  22. 

r 

Hand  reg- 

Automatic 

Grates 

Grates 

Conditions,                           \ 

ulation  of 
draught. 

regula- 
tion of 

with   50 
per  cent. 

with  60 
per  cent. 

I 

draught. 

air   space. 

air   space. 

Manner  of  start  and  stop, 

Ordinary. 

Ordinary. 

Ordinary. 

Ordinary. 

Kind  of  run,          .        .      | 

Continu- 
ous. 

Continu- 
ous. 

Contimf- 
ous. 

Continu- 
ous. 

Duration,       .        .        .  hrs. 

10.2 

10 

9.5 

9.7 

Coal  consumed    (including 

wood  equivalent,  )     Ibs. 

937 

980 

,623 

1,643 

Percentage  of  ash,  per  cent. 

13.1 

14.1 

12  5 

13.9 

Water  evaporated,        .   Ibs. 

8,638 

9,263 

15,935 

15,597 

Coal  per  hour,       .        .  Ibs. 

91.9 

91.3 

170.8 

168.5 

Coal  per  hour    per    square 

foot  of  grate,         .  Ibs. 

4.7 

4.7 

8  7 

8.6 

Water  per  hour,    .        .   Ibs. 

846.9 

926.3 

1,677.3 

1,607.9 

Water  per  hour  per  square 

foot    of    water-heating 

surface,          .        .   Ibs. 

1.3 

1.4 

2.3 

2.3 

Horse-power  developed,  H  .  P. 

25.1 

27.8 

50.3 

48.2 

Boiler  pressure,    .        .Ibs. 

46 

47 

47 

46 

Temperature  of  feed-water, 

deg. 

200 

200 

203 

200 

Temperature     of     escaping 

gases,     .         .        .  deg. 

297 

299 

340 

348 

Water  per  pound  of  coal,  Ibs. 

9.22 

9.45 

9.83 

9.49 

Water  per  poundof  coalfrom 

and  at  212  degrees,  Ibs. 

9.57 

9.81 

10.17 

9.85 

Water  per  pound   of  com- 

bustible from  and  at  212 

degrees,          .        .  Ibs. 

11.01 

11.42 

11  63 

11.44 

Tests  No.  19  and  No.  20,  made  on  Boiler  No.  10,  had  for 
an  object  the  determination  of  the  economy  of  automatic  regu- 
lation of  the  draught  over  hand  regulation.  On  the  test  with 
hand  regulation  the  method  pursued  was  to  alternately  open 
and  shut  the  damper  through  its  full  range  during  the  whole 
progress  of  the  test.  When  the  damper  was  open  it  was  kept 
in  this  position  till  the  steam  pressure  rose  to  a  certain  figure 
determined  upon  beforehand.  It  was  then  closed  and  kept  in 
that  position  till  the  pressure  fell  to  a  certain  lower  figure. 
Test  No.  19  gives  the  average  of  three  trials,  on  the  first  of 
which  the  variation  in  pressure,  in  the  manner  noted,  amounted 
to  4  pounds,  on  the  second,  7  pounds  and  on  the  third  1 
pound.  On  the  test  with  automatic  regulation  the  type  of 


BOILER  No.   10.  95 

regulator  employed  was  that  in  which  the  pressure  acts  through 
a  diaphragm  and  a  system  of  levers  upon  the  damper.  The 
extreme  variation  of  pressure  was  limited  to  2  pounds.  A 
comparison  of  the  results  of  these  tests  shows  that  the  automa- 
tic regulation  secured  an  improvement  over  hand  regulation 
amounting  to  2.5  per  cent,  based  on  coal,  and  3. 7  percent, 
based  on  combustible.  It  is  a  difficult  matter  to  show  by 
means  of  a  test  the  working  economy  produced  by  automatic 
regulation,  because  so  much  depends  upon  the  personal  element 
when  the  draught  is  controlled  by  hand.  On  such  a  test,  the 
fireman  may  have  an  incentive  to  do  his  best,  which  he  might 
not  have  in  ordinary  work.  For  this  reason  the  tests  reveal 
the  tendency  which  automatic  regulation  has  to  secure  economy, 
rather  than  the  actual  gain  which  may  be  secured  under  work- 
ing conditions.  In  this  connection  it  may  be  added  that  tests 
were  made  on  two  large  plants  of  boilers,  to  determine  the 
economy  of  automatic  regulation  over  hand  regulation,  and 
in  one  case  the  result  was  favorable  to  automatic  regulation, 
while  in  the  other  case  it  was  favorable  to  hand  regulation. 

The  object  of  Tests  No.  21  and  No.  22  was  to  determine  the 
effect  which  the  type  of  grates  may  have  upon  the  economy. 
The  principal  difference  in  the  two  grates  lay  in  the  proportion 
of  air  space.  Both  tests  were  made  with  automatic  regulation 
of  the  draught.  The  grates  with  50  per  cent,  air  space  gave 
3.2  per  cent,  better  result  based  on  coal,  and  1.7  per  cent, 
better  result  based  on  combustible,  than  the  grates  with  60  per 
cent,  air  space.  Subsequent  tests  were  made  under  similar 
conditions,  with  a  slower  rate  of  combustion.  In  this  case  the 
gain  due  to  the  smaller  air  space  was  more  marked,  being 
about  8  per  cent.  From  this  showing  it  may  be  concluded 
that  the  slower  the  rate  of  combustion,  the  smaller  should  be 
the  opening  for  draught  through  the  grates.  The  gain  prob- 
ably comes  about  by  preventing  the  introduction  of  too  great 
an  excess  of  air  over  that  required  for  combustion. 

Comparing  Test  No.  21  with  Test  No.  20,  both  of  which  were 
made  with  the  same  grates,  it  appears  that  the  more  rapid  com- 
bustion on  Test  No.  21  secured  a  noticeable  advantage.  It 


96  BOILEE    TESTS. 

amounted  to  3.6  per  cent,  based  on  coal,  and  1.9  per  cent, 
based  on  combustible.  Taking  into  account  the  slow  rate  of 
combustion  on  Test  No.  20,  which  was  4.7  pounds  per  square 
foot  of  grate  per  hour,  the  performance  of  the  boiler  is  excel- 
lent. This  is  significant  when  the  small  diameter  of  the  shell, 
and  the  age  of  the  boiler  are  taken  into  account. 

Boiler  No.  11. 

Kind  of  boiler,        .        .        .        .        .        .  Horizontal  return  tubular. 

Number  used,  .        .         .       •.         ...  One. 

Horse-power  (basis  12  square  feet),      .        .  Fifty-three. 

Age,          ........  Several  years. 

Boiler  No.  11  is  of  the  ordinary  horizontal  return  tubular 
type.  The  arrangement  of  its  setting  is  in  all  essential  par- 
ticulars like  that  shown  in  the  cuts  of  Boiler  No.  5,  with  the 
exception  that  this  boiler  is  provided  with  a  flush  front.  For 
the  purpose  of  burning  oil,  as  was  done  on  Test  No.  24,  the 
furnace  was  arranged  as  shown  in  longitudinal  section  in  the 
following  cut.  The  oil  burner  consisted  of  a  jet,  having  two 
openings,  one  of  which  was  supplied  with  oil,  and  the  other 
with  steam.  It  was  placed  in  the  mouth  of  the  furnace,  and 
the  oil  was  brought  to  it  by  force  of  gravity.  The  grates  were 
covered  with  fire  brick,  and  at  the  rear  end  of  the  furnace  was 
placed  a  mass  of  loose  bricks,  upon  which  the  flames  of  the 
burner  were  directed.  The  steam  supplied  to  the  burner  was 
superheated  by  passing  it  through  pipes  placed  on  the  bottom 
of  the  furnace,  beneath  the  loose  bricks  referred  to.  The  air 
for  combustion  entered  through  the  doorways  of  the  furnace, 
around  the  pipes  leading  to  the  burner,  and  the  space  sur- 
rounding the  pipes  was  left  open. 


BOILER   No.    11, 


97 


BOILER  No.  11,  LONGITUDINAL  SECTION. 
Dimensions  of  Boiler  No.  11. 

Diameter  of  shell,     ...        . 48 

Length  between  heads  and  length  of  tubes,     ....  15 

Number  of  tubes  3  inches  outside  diameter,    ....  49 

Area  of  heating  surface,  .        •        •      •••'••.-       .         .         .  639 

Area  of  grate  surface,       .       ...       .        .        .       ..'..,.  18 

Area  through  tubes,  .         «         .         .         .         .         .         .         .  2 

Ratio  of  heating  surface  to  grate  surface,  •    .      '.        .        .  35.5  to  1 

Ratio  of  grate  to  tube  area,      .        .        .        .        .       v.    '  '.  8.9  to  1 

Results  of  Tests.     Boiler  No.  11. 


in. 
ft. 

sq.  ft. 
sq.  ft. 
sq.  ft. 


Test  No.  23. 

Test  No.  24. 

Kind  of  fuel,  .         .         .   -  -.  :    •  . 

•{ 

Anthracite 
broken. 

Petroleum 
oil. 

Manner  of  start  and  stop  and  kind  of  r 

un, 

Ordinary. 

Ordinary. 

Duration,      ...... 

.  hrs. 

10 

10 

Fuel  consumed,    ..... 

.   Ibs. 

986 

1,365 

Percentage  of  ash  in  coal,  .         .         .  p 

er  cent. 

15 

_. 

Water  evaporated,       .... 

.   Ibs. 

8,493 

15,787 

Fuel  per  hour,      

.   Ibs. 

98.6 

136.5 

Fuel  per  hour  per  square  foot  of  grate, 

.   Ibs. 

5.7 

_ 

Water  per  hour,  ..... 

.  Ibs. 

849.3 

1,578.7 

Water  per  hour  per   square   foot  of 

heating 

surface,         .         .         .        .  *     . 

.   Ibs. 

1.3 

2  5 

Horse-power  developed,      .        ... 

H.  P. 

25.5 

47.4 

Boiler  pressure,  . 

.  Ibs. 

59 

62 

Temperature  of  feed-water,       .        . 

.  (leg. 

208 

208 

Water  per  pound  of  fuel,  .         . 

.   Ibs. 

8.61 

11.56 

Water  per  pound  of  fuel  from  and  at 

212  cle- 

degrees,         

.   Ibs. 

8.91 

11.96 

Water  per  pound  of  combustible  from 

and  at 

212  degrees,           .         .     :  . 

.    Ibs. 

10.48 

— 

98  BOILER    TESTS, 

The  tests  on  Boiler  No.  11  had  for  an  object  the  determina- 
tion of  the  economy  of  crude  petroleum,  compared  with 
anthracite  coal.  On  the  test  with  petroleum  the  damper  was 
kept  wide  open,  and  the  capacity  of  the  boiler  was  regulated 
by  varying  the  quantity  of  oil  consumed.  On  the  test  with 
coal  the  damper  was  partially  closed.  During  the  oil  test  the 
quantity  of  steam  used  by  the  burner  amounted  to  15  per  cent, 
of  the  total  amount  generated  by  the  boiler,  and  the  quantities 
given  in  the  Table  are  corrected  for  the  steam  thus  used. 

The  results  of  the  tests  show  a  higher  evaporation  per  pound 
of  fuel  in  the  case  of  oil  than  in  the  case  of  coal,  the  increase 
being  34.2  per  cent.  The  quantity  of  fuel  required  to  evapo- 
rate a  given  quantity  of  water — say  30,000  pounds  —  from 
and  at  212  degrees  in  the  two  cases,  according  to  these  results, 
is  3,367  pounds  or  1.5  tons  of  coal,  and  2,509  pounds  or  386 
gallons  of  oil.  The  coal  at  $5  per  ton  costs  $7.50.  The  price 
of  oil  required  to  bring  the  cost  of  386  gallons  up  to  $7.50  is 
1.9  cents  per  gallon.  The  employment  of  a  liquid  fuel  serves 
to  reduce  to  a  minimum  the  labor  attending  the  firing  and  care 
of  a  plant  of  boilers.  A  plant  of  1,000  horse-power,  in  a  mill 
running  10  hours  per  day,  requires  two  firemen  for  day  run, 
two  helpers  for  wheeling  coal,  and  one  night  hand  for  banking, 
removing  ashes,  and  preparing  the  morning  fires.  The  use  of 
oil  suitably  arranged  requires  only  one  man,  and  dispenses 
with  the  labor  of  the  remaining  four.  The  saving  in  cost  of 
labor  thus  realized  represents  about  10  per  cent,  of  the  cost  of 
the  fuel,  assuming  that  coal  is  $5  per  ton  and  12  tons  of  coal 
are  burned  per  day.  This  element  in  the  problem  should  not 
be  disregarded  when  making  a  comparison  of  the  relative 
economy  of  the  two  kinds  of  fuel.  In  the  case  of  these  tests 
it  makes  the  price  of  oil  for  the  plant  noted  2.18  cents  per 
gallon  to  equal  the  performance  of  coal  at  $5  per  ton. 

Boiler  No.   12. 

Kind  of  boiler,         .        .        .        . '  '  ]  •        •  Horizontal  return  tubular. 

Number  used, One. 

Horse-power  (basis  12  square  feet),      .         .  Eighty-seven. 

.         .         .  *       '•         •         •  Eight  months. 


BOILER   No.   12. 


99 


Boiler  No.  12  is  a  horizontal  tubular  boiler,  differing  from 
that  of  the  ordinary  type  in  the  arrangement  of  tubes.  The* 
general  features  of  the  boiler  and  the  manner  in  which  it  is  set 
are  shown  in  the  following  cuts.  The  tubes  are  divided  into 
two  sections ;  one  section  serving  to  carry  the  products  of 
combustion  forward,  as  in  the  ordinary  boiler,  and  the  other 
serving  to  carry  them  backward  to  the  chimney.  The  latter 
are  placed  centrally  with  reference  to  the  former,  and  extend 
backward  from  the  main  tube  sheet  a  distance  of  three  feet, 
the  extended  portion  being  enclosed  in  a  supplementary  shell 
34  inches  in  diameter,  which  forms  an  extension  to  the  rear 
end  of  the  boiler. 

This  arrangement  of  tubes  reduces  the  area  for  draught  in  a 
given  size  of  shell  below  what  it  would  be  in  the  boiler  of  the 
ordinary  type,  inasmuch  as  only  about  one-half  of  the  tubes 
are  effective  in  either  direction.  The  ratio  of  the  grate  surface 
to  the  smallest  tube  area  in  the  boiler  under  notice  is  11.6  to  1. 

The  setting  of  the  boiler  is  so  arranged  as  to  introduce  air 
to  the  products  of  combustion  as  they  leave  the  furnace.  The 
air  is  supplied 
through  pas- 
sages which  ex- 
tend back  and 
forth  through  the 
side  walls,  being 
finally  discharged 
through  perfo- 
rated plates 
located  in  the 
sides  of  the  fur- 
nace and  in  the 
top  of  the  bridge 
wall. 


BOILER  No.  12,  CROSS  SECTION  THROUGH  FURNACE. 


100 


BOILEE   TESTS. 


BOILER  No.  12,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  No.  12. 
Diameter  of  shell, 
Length  of  main  shell  bet' 
Number  of  tubes  three  in 
Length  of  52  tubes,     . 
Length  of  55  tubes,     . 
Area  of  heating  surface, 
Area  of  grate  surface, 
Least  area  for  draught  tli 
Area  through  chimney, 
Height  of  chimney,     . 
Width  of  air  spaces  and 
Distance  of  grate  to  shell, 
Distance  of  bridge  wall  to  shell, 
Ratio  of  heating  surface  to 
Ratio  of  grate  to  tube  area, 


•            •     ~"     •            .             .             • 

.     66 

in. 

reen  heads*        J        . 

.        .     10 

ft. 

;hes  outside  diameter, 

.-       .  107 

...... 

...      .     10 

ft. 

. 

.         .     13 

ft. 

•        .        .        •  '  '      »        • 

v"     1,041 

sq.  ft. 

•    \    •      £  •  "  •    •  '''"    *        • 

•;.  .-.    .     24.7 

sq.  ft. 

*ough  tubes,       .        •      :  • 

...     .       2.1 

sq.  ft. 

2.3 

sq    ft. 

.     95 

ft. 

aetal  bars  in  grates,  .        . 

.  3-8 

in. 

.     23 

in. 

7 

in. 

.     42 

to  1 

.     11.6 

to  1 

BOILEE  No.   12. 
Results  of  Tests.     Boiler  No.   12. 


101 


Test  No.  25. 

Test  No.  26. 

Test  No.  27. 

Test  No.  28. 

Kind  of  coal,    .        .        .  •] 

Lackawan- 
na  broken. 

Lehigh 
broken. 

George's 
Creek 
Cumber- 

2 parts 
Screenings, 
1  part(ieo.'s 

I 

land. 

Creek  Cum- 

Manner  of    start  and   stop 

berland. 

and  kind  of  run,    . 

Ordinary. 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,        .         .         .  hrs. 

10.7 

10.2 

10.7 

11 

Coal  consumed,  dry  (  includ- 

ing  wood    equivalent  )  , 

Ibs. 

3,037 

3,087 

3,730 

3,315 

Percentage  of  ash,  per  cent. 

12 

10.1 

6.6 

16.5 

Water  evaporated,         .   Ibs. 

26,502 

27,441 

34,743 

27,587 

Coal  per  hour,        .         .   Ibs. 

282.5 

301.2 

347 

301.4 

Coal  per  hour  per  square  foot 

of  grate,           .         .  Ibs. 

11 

12.2 

14 

12.2 

Water  per  hour.    .         .   Ibs. 

2,470.9 

2,677.2 

3,231.9 

2,507.9 

Water  per  hour   per  square 

foot  of  heating  surface, 

Ibs. 

2.4 

2.6 

3.1 

2.4 

Horse-power  developed,  H.  P. 

79.5 

88.5 

105.4 

82 

Boiler  pressure,     .         .    Ibs. 

70 

76.6 

77.6 

76.1 

Temperature  of  feed-water, 

deg. 

128 

118 

111 

108 

Temperature     of     escaping 

gases,      .         .        .  deg. 

306 

346 

381 

343 

Draught  suction,  .         .in. 

0.28 

0.28 

0.28 

0.28 

Water  per  pound  of  coal,  Ibs. 

8.75 

8.89 

9.31 

8.32 

Water  per    pound    of    coal 

from  and  at  212  decrees, 

~  Ibs. 

9.80 

10.07 

10.61 

9.51 

Water  per  pound  of  combus- 

tible from  and  at  212  de- 

grees,     .        .         .  Ibs. 

11.13 

11.20 

11.37 

11.40 

NOTE.  —  The  mixed  fuel  when  fired  contained  5  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  12  had  for  an  ol)ject  the  determina- 
tion of  the  general  economy  of  this  particular  form  of  boiler, 
and  the  relative  economy  produced  by  different  kinds  of  fuel. 
The  tests  were  made  with  a  wide  open  damper  and  a  constant 
maximum  draught.  They  were  thus  capacity  tests  as  well  as 
economy  tests.  The  results  obtained  on  Tests  No.  25  and  No. 
26,  made  with  anthracite  coal,  compare  favorably  with  the 
best  performance  of  horizontal  tubular  boilers.  It  is  probable 
that  even  better  results  would  have  been  obtained,  if,  on  these 
tests,  there  had  been  no  air  admitted  above  the  fuel.  In  point 
of  economy  the  particular  arrangement  of  tubes  adopted  ap- 
pears to  have  been  advantageous.  The  low  temperature  of 


ov 
UNIVERSITY 


102  BOILER   TESTS. 

the  waste  gases  shows  that  the  heating  surface  by  this  means 
was  arranged  so  as  to  absorb  the  heat  in  an  efficient  manner. 
The  favorable  performance  of  the  anthracite  coals  is  borne  out 
by  the  result  of  Test  No.  28,  made  with  the  mixture.  It  is  not 
so  well  borne  out  by  the  test  of  the  Cumberland  coal.  Com- 
paring the  different  results  with  that  obtained  on  Test  No.  25, 
made  with  Lackawanna  coal,  there  is  a  gain  for  Lehigh  coal  of 
2.8  per  cent.,  a  gain  for  Cumberland  coal  of  8.2  per  cent., 
and  a  loss  for  the  mixed  fuel  of  3  per  cent.,  the  comparisons 
being  based  on  the  coal  results.  These  differences  seem  to 
be  mainly  due  to  the  different  percentages  of  ash,  for  the 
results  based  on  combustible  have  an  extreme  variation  of 
only  2.5  per  cent.  In  the  matter  of  capacity  the  Lackawanna 
coal  gave  a  trifle  less  than  the  rated  power,  the  Lehigh  gained 
11  per  cent,  over  the  Lackawanna,  the  Cumberland  gained  33 
per  cent,  over  the  same  and  the  mixture  3  per  cent. 

The  temperature  of  the  escaping  gases  in  the  front  connec- 
tion, before  passing  into  the  central  tubes  was  325  degrees 
higher  than  that  in  the  flue  at  the  entrance  to  the  chimney. 

Boiler  No.    13. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used,      ......  One. 

Horse-power  (  basis  12  sq.  ft.  ),         .         .  Fifty-five. 

Kind  of  coal,      ......  Anthracite,  Lcliigh,  Chestnut. 

Age, Sixteen  years. 

Boiler  No.  13  is  the  same  boiler  as  the  return  tubular  boiler 
given  under  the  head  of  Boiler  No.  1,  with  the  exception  that 
the  superheater  had  been  removed.  The  general  form  of  the 
boiler  and  the  arrangement  of  the  setting  are  shown  in  longi- 
tudinal section  in  the  following  cut.  The  tests  here  given  (  Nos. 
29  and  30  ) ,  were  made  one  year  later  than  Tests  Nos.  1  and  2. 


BOILEE  No.  13. 


103 


1-13 


BOILER  No.  13,  LOXGITUDINA 

L  SECTION. 

Dimensions  of  Boiler  No 

.  13. 

Diameter  of  shell,  .        .        .       V       • 

... 

48     in. 

Length  between  heads  and  length  of  tubes, 

. 

10     ft. 

Number  of  tubes  three  inches  outside  diameter, 

. 

48 

Area  of  heating  surface,        .        .        .        . 

. 

000     sq.  ft. 

Area  of  grate  surface,    .        .        ,        . 

. 

10.0  sq.  ft. 

Area  through  tubes,         ,      •  ."       .        . 

. 

2     sq.  ft. 

Area  through  flue,    ...... 

1.0  sq.  f 

Height  of  chimney,          .- 

. 

77     ft. 

Width  of  air  spaces  and  metal  bars  in  grates, 

.    Air  3-8  in. 

,  metal  5-8  i 

Distance  of  grate  to  shell,      .... 

; 

10     in. 

0     in. 

Ratio  of  heatin0'  surface  to  °Tate  surface, 

33.7  to  1 

Ratio  of  grate  to  tube  area,    .... 

.         i 

10     to  1 

Results  of  Tests,  Boiler  JV 

o.  13. 

Test  No.  29. 

Test  No.  30. 

Conditions,  

Damper 
wide  open. 

Damper 
partly  open. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      .......  hrs. 

11 

11 

Coal  consumed,  (  including  wood  equivalent,) 

Ibs. 

2,G47 

1,430 

Percentage  of  ash,      ....  per  cent. 

10  4 

17.5 

Water  evaporated,       Ibs. 

10,053 

10,731 

Coal  per  hour,      Ibs. 

2400 

130 

Coal  per  hour  per  square  foot  of  grate,        Ibs. 

12.1 

0.5 

Water  per  hour,  ......  Ibs. 

1,780.6 

075.6 

Water  per  hour  per  square  foot  heating  surface, 

Ibs. 

2.7 

1.5 

Horse-power  developed,                                H.  P. 

02.1 

33.0 

Boiler  pressure,  .        .        .                 .        .   Ibs. 

71.9 

00.5 

Temperature  of  feed-water,       .        .        .  deg. 

40 

40 

Temperature  of  escaping  gases,         .        .  deg. 

444 

350 

Water  per  pound  of  coal,  ....   Ibs. 

7.42 

7.50 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,         "   .        .  ibs. 

8.99 

9.08 

Water  per  pound  of  combustible  from  and  at 

212  degrees,           Ibs. 

"10.76 

11  01 

104  BOILEE    TESTS. 

The  object  of  the  tests  on  Boiler  No.  13  was  to  determine 
the  effect  of  two  widely  different  rates  of  combustion.  In  Test 
No.  29,  the  rate  was  12.1  pounds  per  square  foot  of  grate  per 
hour,  and  in  Test  No.  30  it  was  6.5  pounds,  one  giving  a  slight 
excess  above  the  nominal  power,  and  the  other  a  much  lower 
capacity.  The  difference  in  the  economic  results  of  the  two 
tests  in  favor  of  the  slow  rate  of  combustion  is  one  per  cent, 
based  on  coal,  and  2.3  per  cent,  based  on  combustible.  There 
is  a  noticeable  difference  in  the  two  tests  in  the  temperature  of 
the  waste  gases.  The  excessive  temperature  with  the  high 
rate  of  combustion,  taken  in  connection  with  the  age  of  the 
boiler,  gives  evidence  of  the  presence  of  scale  on  the  heating 
surfaces.  Had  the  surface  been  of  sufficient  extent,  or  in  such 
.a  condition  as  to  absorb  this  heat,  the  comparison  between  the 
two  tests  would  undoubtedly  have  been  in  favor  of  rapid  com- 
bustion. 

Boiler  No.    14. 

(Kind  of  boiler,  .        .        .     :-»       .«        .  Horizontal  direct  tubular. 

Number  used,     ......  One. 

Horse-power  (basis  12  square  feet),        .  Fifty-two. 

Kind  of  coal, Anthracite,  Lehigh,  Chestnut. 

_&ge,    ........  Sixteen  years. 

Boiler  No.  14  is  the  same  boiler  as  that  referred  to  as  the 
direct  tubular  boiler  under  the  head  of  Boiler  No.  1,  the  tests 
being  made  one  year  later.  The  general  arrangement  of  the 
boiler  and  the  manner  in  which  it  is  set  are  shown  in  longitu- 
dinal section  in  the  following  cut. 

In  this  boiler  the  products  of  combustion  pass  upward  from 
the  furnace  into  a  combustion  chamber  situated  in  the  front 
end  of  the  shell,  then  forward  through  the  tubes,  then  back- 
ward under  the  shell  to  the  furnace  wall,  and  finally  upward 
through  two  side  flues  and  over  the  top  of  the  rear  part  of  the 
shell  to  the  chimney  flue.  The  upper  part  of  the  shell  last 
traversed  furnishes  steam-heating  surface.  This  surface  is 
probably  inefficient,  owing  to  the  deposit  of  soot  which  nat- 
urally covers  it.  The  boiler  is  fitted  with  a  steam  dome. 


BOILEE  No.   14. 


105 


BOILER  No.  14,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  N'o.  14. 

Diameter  of  shell,  .        .      •  .        .        .        .       •  ."  '     v        .  48     in. 

Length  between  heads  and  length  of  tubes,         = .      x  .  .      . .  14     ft. 

Number  of  tubes  3  inches  outside  diameter,      -    ,        .        .  45 

Length  of  combustion  chamber,     .        .        .      • .        ,        .  38     in. 

Inside  diameter  of  combustion  chamber,       .         .       •.      -  .  42     in. 

"Diameter  of  two  openings  to  combustion  chamber,      ..".,.  14     in. 

Area  of  water-heating  surface,       .         .        .        >         .         .  58G     sq.  ft. 

Area  of  steam-heating  surface,       .         .         ....         .  43     sq.  ft. 

Area  of  grate  surface,    .        ;  :     .      y. .   ...     .        .    .    .  21.2  sq.  ft. 

Area  through  tubes,          .         .-«...,.        «         .  1.9  sq.  ft. 

Area  through  flue,   .         .         .       , .         ,         .         .         .         .  2.2  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,       .     Air  3-8  in.,  metal  5-8  in. 

Distance  of  grate  to  shell,      .        .        ...        .        .  17     in. 

Height  of  chimney,         .  .    :  .        .      ....         .         .  77     ft. 

Katio  of  water-heating  surface  to  grate  surface,  ....        .,  -  27.7  to  1 

Ratio  of  grate  to  tube  area,    .        ...        .  11. 4  to  1 


106 


BOILER    TESTS. 
Results  of  Tests,  Boiler  No.  14. 


Test  No.  31. 

Test  No.  32. 

Conditions,  .        ....        »        .      •< 

Damper  wide 
open. 

Damper  partly 
closed. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,     hrs. 

11.2 

10.7 

Coal  consumed,    (including  wood  eqiva- 

2,731 

1,367 

lent,  )    Ibs. 

Percentage  of  ash,     .        .        .  per  cent. 

15.7 

15.5 

Water  evaporated,       .         .         .         .Ibs. 

19,891 

10,388 

Coal  per  hour      Ibs. 

242.8 

127.2 

Coal  per  hour  per  square  foot  of  grate, 

Ibs. 

11.4 

6 

Water  per  hour,  .         .         .         .         .   Ibs. 

1,768.1 

966.3 

Water  per  hour  per  square  foot  of  water- 

heating  surface,    ....   Ibs. 

3 

1.6 

Horse  power  developed,      .        .        H.  P. 

61.4 

33.5 

Boiler  pressure,  Ibs. 

67.7 

65.2 

Temperature  of  feed-water,       .         .  deg. 

40 

40 

Temperature  of  escaping  gasas,        .  deg. 

476 

380 

Water  per  pound  of  coal,  .         .         .   Ibs. 

7.28 

7.60 

Water  per  pound  of  coal  from  and  at  212 

degrees,         .....   Ibs. 

8.82 

9.19 

Water  per  pound  of  combustible  from  and 

at  212  degrees,      .         .                 .   Ibs. 

10.46 

10.88 

The  tests  on  Boiler  No.  14  like  those  on  No  13,  were  made 
to  determine  the  effect  produced  by  two  widely  different  rates 
of  combustion.  In  Test  No.  31  the  rate  was  11.4  pounds  of 
coal  per  square  foot  of  grate  per  hour,  and  in  Test  No.  32  it 
was  6  pounds,  one  giving  a  somewhat  larger  amount  of  power 
than  the  rated  boiler  power,  and  the  other  a  much  lower 
amount.  The  economical  result  obtained  with  the  low  capac- 
ity is  the  better  of  the  two  to  the  extent  of  4.2  per  cent. 
There  is  a  noticeable  difference  in  the  two  tests  in  the  tempera- 
ture of  the  escaping  gases,  one  being  476  and  the  other  380 
degrees.  To  this  difference  is  evidently  due  the  comparatively 
low  economy  produced  by  the  rapid  combustion.  Comparing 
these  results  with  those  obtained  from  Boiler  No.  13,  they  are 
inferior,  as  might  be  expected  from  the  difference  in  the  quan- 
tity of  heating  surface,  and  the  resulting  higher  temperature  of 
the  waste  gases.  There  is  20  per  cent,  less  heating  surface  in 
proportion  to  grate  in  this  boiler,  than  in  Boiler  No.  13. 


BOILER   No.  15. 


107 


Boiler  No 

Kind  of  boiler, 

Number  used, 

Horse-power  (basis  12  square  feet),  . 
Kind  of  coal,      .         .        .       ..   .    ,.-      ;. 

Age,    .         .         .         . •  -    .  .        . 

Boiler  Xo.  15  is  similar 
in  general  features  to  Boil- 
er Xo.  9,  being  provided 
with  a  water  leg  front, 
which  takes  the  place  of 
the  ordinary  cast  iron  front 
with  brick  lining.  The 
general  arrangement  of  the 
boiler  and  the  manner  in 
which  it  is  set  are  shown 
in  the  following  cuts.  It 
is  to  be  noted  that  the 
space  behind  the  bridge 
wall  is  unusually  deep, 


15. 

Horizontal  return  tubular. 
One. 

Seventy-four. 

Anthracite,  Lehigh,  Chestnut. 
One  year. 


BOILER  No.  15,  CROSS  SECTION  THROUGH 

FURNACE. 

extending  a  distance  of  7  feet  below  the  shell,  and  one  of  the 
side  walls  is  exposed  on  the  outside  a  corresponding  distance. 


BOILER  No.  15,  LONGITUDINAL  SECTION. 


108 


BOILER   TESTS. 


Dimensions  of  Boiler  No.  15. 

Diameter  of  shell,      .        . 60      in. 

Length  between  heads  and  length  of  tubes,    .        .        .        .  15      ft. 

Number  of  tubes  3  inches  outside  diameter,    ....  66 

Area  of  heating  surface,  .        .       ..      ' 890      sq.  ft. 

Area  of  grate  surface,       •  •'.-•>      -.      •,        .        .        .        .  24.1  sq.  ft. 

Area  through  tubes,  .        .  ....       .        ...         .         .         .  2.7  sq.  ft. 

Area  through  flue,      .       ,.',..        .         .         .         .         .  2.4  sq.  ft. 

Height  of  chimney,  .;.       ->-.--.        ,   ''    v        .        .        .77      ft. 
Width  of  airspaces  and  metal  bars  in  grates,  Air  3-8  in.,  metal  5-8    in. 

Distance  of  grate  to  shell,         *.  '    .        .        ..,"..'       .  23      in. 

Distance  of  flat  bridge  wall  to  shell,        ...'..,     .       ...  7      in. 

Ratio  of  heating  surface  to  grate  surface,.      ,:        .      '  .        .  37     to  1 

Ratio  of  grate  to  tube  area,       ...        .        .    .     .  ,      .        .  10     to  1 

Results  of  Tests,  Boiler  No.  15. 


Test  No.  33. 

Test  No.  34. 

( 

Damper 

Damper 

Conditions,  .        .        .        ...        .      4 

wide  open. 

partly 

{ 

closed. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      .......  hrs. 

12 

11 

Coal  consumed  (  including  wood  equivalent  ), 

Ibs. 

4,099 

2,659 

Percentage  of  ash,      .        .'"'•  .        .  percent. 

14.4 

14.2 

Water  evaporated,       *       -.        .        .        .   Ibs 

30,326 

20,244 

Coal  per  hour      .         .        «        .        .        .   Ibs 

341.6 

241.7 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs 

14.2 

10 

Water  per  hour,  Ibs. 

2,527.2 

1,840.4 

Water  per  hour  per  square  foot  of  heating  sur- 

face,         Ibs. 

2.8 

2.1 

Horse-power  developed,      .        .        .         H.  P. 

87.8 

64 

Boiler  pressure    ......   Ibs. 

73.8 

70 

Temperature  of  feed-water,       .        .         .  deg. 

40 

40 

Temperature  of  escaping  gases,         .        .  deg. 

365 

350 

Water  per  pound  of  coal,  ....   Ibs. 

7.40 

7.61 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,   .......   Ibs. 

8.97 

9.22 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  .         .         .         .       --.         .   Ibs. 

10.47 

10.75 

The  tests  on  Boiler  No.  15,  together  with  those  made  on 
Boilers  No.  13  and  14,  form  a  group  of  tests,  the  object  of 
which  was  to  determine  the  relative  economy  of  working  to 
maximum  capacity  and  to  medium  capacity,  in  the  case  of  three 
boilers  of  somewhat  different  types.  All  used  coal  from  the 
same  cargo.  In  the  case  of  Boiler  No.  15,  as  in  those  of  No. 


BOILER  No.   15.  109 

13  and  No.  14  already  noted,  there  is  an  appreciable  difference 
of  economy  in  favor  of  the  medium  capacity.  Here  it  is  about 
three  per  cent.  There  is  a  notably  low  temperature  of  the 
escaping  gases  compared  with  that  found  in  the  other  two 
boilers  worked  at  maximum  capacity,  due,  no  doubt,  in  part, 
to  the  relatively  large  extent  of  heating  surface,  and  in  part  to 
the  cleanliness  of  the  surfaces  which  presumably  existed  in  the 
new  boiler.  Still,  this  favorable  indication  is  accompanied  by 
a  comparatively  low  evaporative  result.  The  large  space 
behind  the  bridge  and  the  greater  radiating  surfaces  thus 
exposed  does  not  appear  to  be  adequate  to  produce  an  unfav- 
orable effect  of  much  consequence,  but  there  appears  no  other 
cause.  It  is  noted  that  a  higher  rate  of  combustion  is  secured 
in  Boiler  No.  15  than  in  the  others.  This  may  be  attributed 
to  the  newer  and  tighter  condition  of  the  flues  leading  to  the 
chimney.  One  chimney  of  ample  area  served  for  all  three 
boilers. 

A  series  of  tests  was  made  on  Boiler  No.  15  to  compare  the 
economy  of  different  fuels.  These  are  numbered  from  35  to 
39  inclusive.  With  the  exception  of  Test  No.  39  made  with 
mixed  fuel,  none  of  these  are  capacity  tests.  On  all  the  tests 
except  this  one,  the  damper  was  partially  closed.  The  results 
are  given  in  the  appended  table. 

Taking  the  results  with  chestnut  coal  as  a  basis  of  compari- 
son, and  figuring  on  the  evaporation  per  pound  of  coal,  the 
pea  coal  lost  9  per  cent.  ;  the  broken  coal  gained  4.2  per  cent.  ; 
the  Cumberland  coal  gained  19.3  per  cent.,  and  the  mixed  fuel 
gained  6.2  per  cent. 

Considering  the  cost  of  these  fuels  given  below,  as  quoted 
at  the  time  of  the  tests  (  per  ton  of  2,240  pounds  ), 

Chestnut,        . .  $5  50 

Pea, 4  60 

Broken,          .        .        .         c 5  85 

Pea  and  Dust, 2  75 

Cumberland,          .         .         .         .         .         .                  .  G  50 

the  total  value  of  the  fuel  used  in  evaporating  a  given  quantity 
of  water,  say  30,000  pounds  from  and  at  212  degrees,  accord- 
ing to  the  results  here  obtained,  is  as  follows  : 


110 


BOILEE    TESTS. 


Ob-         O 


o  >—  i  co  »o  r-i 


JIfl       « 


GO          0  00  CO          00 


o 

:i; 

§•!*• 

§      g*a 


&  <M 

O>    rH 
O    CM 

cJ,-2 

0)    c3 


±3 

ci   0 


i 

ill! 


BOILEE  No.  15.  HI 

Chestnut, .  $8  00 

Pea, 7  32 

Broken, 8  15 

Cumberland, 791 

Mixed  fuel, 5  48 

According  to  this  basis  of  comparison,  which  may  be  called 
the  commercial  basis,  the  cost  with  pea  coal  is  reduced  $0.32 
or  8.5  per  cent.  ;  that  with  broken  coal  is  increased  $0.15,  or 
1.9  per  cent. ;  that  with  Cumberland  is  reduced  $0.09,  or  1.1 
per  cent.  ;  and  that  with  the  mixture  is  reduced  $2.52,  or  31.5 
per  cent.,  these  being  all  compared  with  the  cost  when  using 
chestnut  coal.  Although  this  comparison  does  not  apply  to 
the  present  time,  when  prices  of  coal  are  altogether  different, 
the  figures  are  suggestive  as  to  the  influence  which  cost  has 
upon  the  actual  value  of  a  given  kind  of  coal. 

The  varying  amounts  of  ash  which  different  sizes  of  anthra- 
cite coal,  and  the  different  classes  of  other  coals  contain,  is 
exhibited  by  these  tests.  The  pea  coal  contained  the  largest 
quantity,  viz  :  15.8  per  cent.  ;  and  the  broken  coal  the  smallest 
for  the  anthracite  class,  viz  :  10.5  per  cent ;  while  the  bitumi- 
nous George's  Creek  Cumberland  gave  6.6  per  cent;  and  the 
mixed  fuel  11.4  per  cent.  The  last  is  low  for  this  class  of 
fuel  and  an  indication  of  good  quality.  There  is  a  noticeable 
difference  in  the  effect  of  the  various  fuels  on  the  temperature 
of  the  escaping  gases.  The  Cumberland  and  mixed  fuels  gave 
a  higher  temperature  than  that  produced  by  the  anthracite 
coals.  This  condition  is  almost  always  observed  in  fuels  made 
up  in  whole  or  in  part  of  bituminous  coal. 

Another  series  of  tests  was  made  on  Boiler  No.  15,  the 
object  of  which  was  to  determine  the  effect  upon  the  economy 
of  different  fuels  produced  by  admitting  air  at  the  bridge  wall. 
These  are  numbered  from  40  to  45  inclusive,  and  the  data  and 
results  are  given  in  the  appended  table.  The  method  employed 
in  supplying  air,  consisted  in  introducing  it  through  a  pipe  7 
inches  in  diameter  running  through  the  side  wall,  at  a  distance 
of  20  inches  below  the  top  of  the  bridge  Avail.  The  pipe 
entered  a  chamber  formed  by  building  a  new  wall  a  few  inches 
behind  the  bridge  and  covering  the  top  of  the  intervening 


112 


BOILEE    TESTS. 


05 


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C1"1  Ci  i-H  CO  If5  >—  1 

^2  I-         10  (M 

^  <N    <N 

o 


&   ° 


-=       ei  050000  cccoi-c        r-i       ^H 

a          CI-H         CO         <M(M         O  OOCOQO  1-1         i-l 

T3  CO         10  (N         0  CO 


'w       s3*£ 

'S      ff      £ 
'-0    '2    "  ST 


fc/J 


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1  •£  -1 

c3       ^       In 


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«  '§  '  .  '--W-    "s 

'3       c^     'O       k  -S  o  °       o 


BOILEE  No.   15.  113 

space  with  a  perforated  iron  plate,  which  was  placed  on  a  level 
with  the  top  of  the  bridge.  A  damper  located  in  the  pipe, 
was  wide  open  when  Cumberland  coal  was  used  and  about 
half-way  open  with  the  other  fuels. 

The  effect  upon  the  economic  result  produced  by  the  admis- 
sion of  air  at  the  bridge  was  quite  marked  in  the  cases  of  the 
Cumberland  coal  and  mixed  fuel ,  but  not  so  in  that  of  the 
anthracite  coal.  The  evaporation  per  pound  of  combustible 
was  increased  6.2  per  cent,  with  Cumberland  coal,  but  it  was 
decreased  4.7  per  cent,  with  the  mixed  fuel.  There  was  little 
difference  produced  with  anthracite  coal. 

In  every  case  the  admission  of  air  was  accompanied  by  an 
increased  temperature  of  the  escaping  gases  and  a  decreased 
amount  of  power  developed.  These  differences  are  small,  but 
they  are  always  in  the  same  direction. 

The  character  of  the  combustion,  as  seen  by  the  eye  of  an 
observer  looking  through  a  peek  hole  into  the  space  behind 
the  bridge  wall,  was  always  improved  by  the  admission  of 
air. 

The  effect  of  admitting  air  upon  the  Cumberland  coal  was 
to  reduce  the  quantity  and  density  of  the  smoke  discharged  at 
the  top  of  the  chimney.  There  was  entire  absence  of  smoke 
^~}  of  the  time  when  air  was  admitted,  and  y^~  of  the  time 
when  air  was  not  admitted.  There  was  little  smoke  in  either 
case  with  mixed  fuel. 

There  was  no  appreciable  difference  in  the  quantity  of  soot 
deposited  in  the  tubes,  as  shown  by  examination  at  the  front 
ends  after  each  test,  whether  air  was  admitted  at  the  bridge  or 
not. 

The  draught  suction  at  the  bottom  of  the  chimney  was 
ordinarily  ^  of  an  inch,  expressed  in  terms  of  water  pressure. 
In  the  boiler  flue  it  was  |  of  an  inch  with  wide  open  damper, 
and  in  the  space  behind  the  bridge  wall  fy  of  an  inch. 

Boiler  No.  16. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used, One. 

Horse-power  (basis  12  square  feet),      .        .  S3venty-flve. 

Age, Two  years. 


114 


BOILER    TESTS. 


Boiler  No.  16  is  of  the  ordinary  horizontal  return  tubular 
type,  with  a  flush  front,  the  setting  of  which  is  shown  in 
longitudinal  section  in  the  cut.  This  boiler  was  one  of  a  large 
battery,  and  during  the  progress  of  the  tests  the  boiler  on  each 
side  was  in  daily  use. 


BOILER  No.  16,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  No.  16. 

Diameter  of  shell, 

Length  between  heads  and  length  of  tubes,    .  .  .  , 
Number  of  tubes  three  inches  outside  diameter,     . 
Area  of  heating  surface, 
Area  of  grate  surface,     .        .        .        ...        *J'. 

Area  through  tubes,      P    .      ,.        . 

Area  through  flue, • '.  . 

Height  of  chimney, ;•• 

Width  of  air  spaces  and  metal  bars  in  grates,     ; '•»•;) 

Distance  of  grate  to  shell, 

Distance  of  flat  bridge  to  shell,      . 

TCatio  of  heating  surface  to  grate  surface,     . 

Katio  of  grate  surface  to  tube  area, 


GO     in. 

15      ft. 

70 
900      sq.  ft 

26.7  sq.  ft 
2.9  sq.  ft 
3  sq 
120 

3-8 

20 


ft. 


ft. 

in. 

in. 
G      in. 
33.8  to  1 
92.  to  1 


BOILER  No.   16. 
Results  of  Tests,  Boiler  No.  16.     (  Average  of  two.  ) 


115 


Test  No.  46. 

Test  No.  47. 

Test  No.  48. 

f 

Anthracite 

Anthracite 

2  parts  Pea  and 

Kind  of  coal,        .        .        .      < 

Stove. 

Chestnut  No.  2. 

Dust,  l  part 

Clearfield. 

Manner  of  start  and  stop  and  kind 

Ordiuarv- 

Ordinary. 

Ordinarv. 

Duration,       .         .         .        .  hrs. 

10  .*7 

11 

10.7 

Coal    consumed,  dry    (including 

wood  equivalent),          .    Ibs. 

2,661 

2,700 

2,789 

Percentage  of  ash,        .  per  cent. 

14.7 

12.8 

14 

Water  evaporated,         .        .   Ibs. 

21,213 

21,350 

22,030 

Coal  per  hour,       .        .        .  Ibs. 

247.7 

245.5 

259.4 

Coal  per  hour  per  square  foot  of 

°Tata       ....   Ibs. 

9.3 

9.6 

9.7 

Water  per  hour,    .        .        .Ibs. 

1,974.4 

1,941 

2,049.3 

Water   per  hour  per  square  foot 

of  heating  surface,        .   Ibs. 

22 

2.2 

2.3 

Horse-power  developed,        H.  P. 

669 

65.8 

69.3 

Boiler  pressure,     .         .         .   Ibs. 

65.8 

64.8 

67.9 

Temperature  of  feed-water,  deg. 

67 

66.5 

71 

Temperature   of  escaping  gases, 

deg. 

314 

312 

326 

Number  of  firings, 

20 

37 

39 

Number  of  times   slice  bar  was 

used,       

1 

1 

12 

Position  of  damper,     . 

^t  open. 

%  open. 

%  open. 

Water  per  pound  of  coal,     .   Ibs. 

7.97 

7.90 

7.90 

Water  per  pound    of  coal  from 

and  at  212  degrees,       .  Ibs. 

9.48 

9.34 

9.31 

Water  per  pound  of  combustible 

from  and  at  212  degrees,  Ibs. 

11.06 

10.72 

10.85 

NOTE.  —  The  mixed  fuel  when  fired  contained  4  1-2  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  16  had  for  an  object  the  determi- 
nation of  the  relative  economy  of  three  different  kinds  of  coal, 
viz  :  anthracite  stove  coal,  anthracite  chestnut  No.  2,  and  a  mix- 
ture of  two  parts  pea  and  dust  and  one  part  Clearfield  bitumi- 
nous. On  the  first  two  tests  the  damper  was  one-fourth  open ; 
on  the  test  with  the  mixed  fuel  the  damper  was  open  halfway, 
and  in  all  cases  the  damper  was  kept  in  a  fixed  position.  The 
evaporative  results  of  the  three  tests,  based  on  coal,  are  almost 
identical.  The  various  results  based  on  the  cost  of  fuels 
required  to  evaporate  30,000  pounds  of  water  from  and  at  212 
degrees,  according  to  the  prices  which  ruled  at  the  time  the 
tests  were  made,  are  as  follows : 


116 


BOILEE    TESTS. 


Stove. 

Chestnut 
No.  2. 

Mixture. 

Cost  per  ton  of  2,240  pounds, 

$5  40 

$  4  50 

$3  70 

Cost  of  fuel  for  30,000  pounds  of  steam,  . 

7  63 

6  42 

5  33 

A  comparison  of  these  figures  shows  that  the  cost  of  making 
a  given  amount  of  steam  with  chestnut  No.  2  coal  was  16 
per  cent,  less  than  with  stove  coal,  and  the  cost  with  the  mix- 
ture was  30  per  cent.  less. 

It  is  noticeable  in  the  case  of  the  test  with  mixed  fuel  that 
the  labor  of  firing  wras  greater  than  that  with  either  of  the 
other  coals.  There  were  39  firings  with  the  mixed  fuel, 
against  20  with  the  stove  coal  and  37  with  chestnut  No.  2  coal, 
while  the  number  of  times  the  slice  bar  was  used  was  12  with 
mixed  fuel,  and  only  one  in  each  case  with  the  others. 

The  low  temperature  of  the  escaping  gases  is  noticeable  in 
these  tests.  Th'is  is  an  indication  of  economical  work  which 
the  favorable  character  of  the  evaporative  results  plainly 
bears  out. 


Boiler  No.  1  7. 

Kind  of  boiler,    ......        Horizontal  return  tubular. 

Number  used,      .        .        .        .        .        .        Three. 

Horse-power  (collective  basjs  12  square  feet),  One  hundred  and  twenty-nine. 
Age,     .        .        .        .        .        .  .        Several  years. 

Boiler  No.  17  embraces  three  ordinary  horizontal  tubular 
boilers  set  in  brick  work  in  the  manner  shown  in  the  follow- 
ing cuts.  Two  of  these  boilers  are  set  with  a  furnace  common 
to  both,  and  in  all  three  the  escaping  gases,  after  leaving  the 
smoke  arches  in  front,  pass  over  the  tops  of  the  shells.  The 
three  boilers  are  end  boilers  of  the  battery,  and  the  next  boiler 
in  the  set  was  in  daily  operation  during  the  progress  of  the 
tests. 


BOILER   No.   17. 


117 


BOILER  No.  17,  CROSS  SECTION  THROUGH  FURNACE. 


y//////////////////^^^^ 


U 


17  __- 


BOILER  No.  17,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  No.  17. 

Diameter  of  shell,  .  •      .        ; 48      in. 

Length  between  heads  and  length  of  tubes,  .         .        .         .  12      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,  147 

Area  of  water-heating  surface, 1,548        sq.  ft. 

Area  of  steam-heating  surface, 185       sq.  ft. 

Area  of  grate  surface,    .        .        ....        .        .        .  58.5    sq.  ft. 

Area  through  tubes,         .         .         .        .        ...»  6.1    sq.  ft. 

Height  of  chimney,         .         .      .   '.        .    .    .        .         .         .  140      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,       Air  7-16  in.,  metal  3-8  in. 

Distance  of  grate  to  shell,      .......  16       in. 

Distance  of  flat  bridge  to  shell,      .        .        .'*,'".,        .  5        in. 

Ratio  of  water-heating  surface  to  grate  surface,           .        .  26.5  to  1 

Ratio  of  grate  to  tube  area, *  9.6  to  1 


118 


BOILER    TESTS. 

Results  of  Tests,  Boiler  No.  17. 


Test  No.  49. 

Test  No.  50. 

Test  No.  51. 

Anthracite 

Anthracite 

44   parts    Pea 

White  Ash 
Broken. 

Pea. 

and  Dust.  37 
parts  Nova 

Scotia  Culm. 

Manner  of    start  and  stop  and 

kind  of  run,  .... 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,       ....  hrs. 

10.2 

10.5 

10.5 

Coal  consumed,    dry    (  including 

wood  equivalent  )  ,          .   Ibs. 

7,848 

6,584 

7,595 

Percentage  of  ash,        .  per  cent. 

10.1 

20.9 

17.9 

Water  evaporated,        .        .   Ibs. 

56,715 

45,071 

47,452 

Coal  per  hour,       .        .        .  Ibs. 

756.6 

627 

723.3 

Coal  per  hour  per  square  foot  of 

grate,      ....   Ibs. 

12.9 

11.7 

13.6 

Water  per  hour,    .         .        .Ibs. 

5,532.6 

4,292.4 

4,519.2 

Water  per  hour  per  square  foot  of 

water-heating  surface,      Ibs. 

3.6 

2.8 

2.9 

Horse-power  developed,        H.  P. 

192.3 

149.2 

157.1 

Boiler  pressure,    .         .         .   Ibs. 

73.7 

74.2 

73 

Temperature  of  feed-water,  deg. 

39 

39 

39 

Temperature  of  escaping  gases, 

deg. 

455 

448 

460 

Draught  suction,  .        .        .in. 

0.11 

0.12 

0.28 

Number  of  firings, 

23 

27 

34 

Number  of  times  using  slice  bar 

or  hoe,    .         .         .               '  .< 

6 

5 

24 

Water  per  pound  of  coal,     .  Ibs. 

7.23 

6.84 

6.24 

Water  per  pound   of    coal  from 

and  at  212  degrees,     .   Ibs. 

8.77 

8.29 

7.57 

Water  per  pound  of  combustible 

from  and  at  212  degrees,  Ibs. 

9.75 

10.63 

9.34 

NOTE. —The  pea  coal  when  fired  contained  5  per  cent.  01  moisture  aud  the  mixture 
10  per  cent. 

The  tests  on  Boiler  No.  17  had  for  a  main  object  the  deter- 
mination of  the  relative  economy  of  three  different  kinds  of 
fuel,  viz  :  anthracite  broken  coal,  anthracite  pea  coal,  and  a 
mixture  of  pea  and  dust  and  Nova  Scotia  culm.  In  general, 
the  results  do  not  show  a  high  degree  of  economy.  In  view 
of  the  small  ratio  of  heating  surface  to  grate  surface,  the  rela- 
tively large  amount  of  power  developed,  compared  with  the 
nominal  power,  and  the  resulting  high  temperature  of  the 
waste  gases,  a  somewhat  unfavorable  result  would  be  expected. 
Comparing  the  performance  of  the  different  fuels,  the  evapora- 
tion with  pea  coal  is  5.5  per  cent,  less  than  that  obtained  with 
broken  coal,  and  the  result  obtained  with  the  mixed  fuel  is 
13.7  per  cent,  less  than  the  same  figure,  these  being  based  on 


BOILER   No.   17. 


119 


the  evaporation  per  pound  of  coal.  Basing  the  results  on  the 
cost  of  fuel  required  to  produce  30,000  pounds  of  steam  from 
and  at  212  degrees,  according  to  the  prices  which  ruled  at  the 
time  of  the  tests,  the  figures  are  as  follows : 


Broken. 


Pea. 


Mixture. 


Cost  per  ton  of  2,240  pounds,      .         . 
Cost  for  30,000  pounds  of  steam,        .        . 

$6  10 
9  32 

|4  75   . 
7  64 

$3  85 
6  81 

In  this  comparison  the  economy  of  pea  coal  is  18  per  cent, 
over  broken  coal,  and  that  of  the  mixture  26.9  per  cent,  over 
the  same  fuel. 

It  is  to  be  noted  that  the  amount  of  draught  required  on  the 
test  with  mixed  fuel  was  0.28  inches  measured  in  water  pres- 
sure, while  that  required  on  the  other  tests  was  0.11  and  0.12 
inches  respectively.  The  labor  of  firing  with  mixed  fuel  was 
much  greater  than  in  the  case  of  the  others,  both  the  number 
of  firings  and  the  number  of  times  that  the  slice  bar  was  used 
being  relatively  large. 

Boiler  No.  18. 

Kind  of  boiler.     .        .        *  .  .  .  Horizontal  return  tubular. 

Number  used,       .        .        .  .  •  •  One. 

Horse-power  (  basis  12  sq.  ft.  )  .  .  .  Fifty-three. 

Age,      .        .        .        .        .    .  .  .  ,  .  Six  months. 

Boiler  No.  18  is  a  horizontal  tubular  boiler  with  a  special 
arrangement  of  setting,  the  general  features  of  which  are 
shown  in  longitudinal  section  in  the  following  cut.  A  furnace 
is  placed  under  each  end  of  the  boiler,  located  in  the  same 
manner  with  reference  to  the  boiler  as  the  furnace  in  the 
common  horizontal  boiler.  A  damper  is  provided  in  each 
front  connection  for  the  control  of  the  flue  gases,  and  another 
above  each  furnace  at  the  entrance  to  the  chamber  in  front  of 
the  tubes,  to  control  the  passage  of  the  products  of  combus- 
tion into  the  boiler.  The  method  of  operation  consists  in 
firing  the  furnaces  alternately.  The  products  of  combustion 


120 


BOILER   TESTS. 


from  either  furnace  are  made  to  pass  over  the  burning  coal  in 
the  other  furnace,  whenever  either  one  is  supplied  with  fresh 
coal.  Just  previous  to  each  firing  the  dampers  are  changed  so 
that  the  desired  result  may  be  secured.  The  fire  in  the 
secondary  furnace  serves  to  heat  and  ignite  the  unburned  gases 
formed  in  the  first. 


BOILER  No.  18,  LONGITUDINAL  SECTION. 


Dimensions  of  Boiler  No.  18. 

Diameter  of  shell, /'     .  " 

Length  between  heads  and  length  of  tubes, 
Number  of  tubes  3  inches  outside  diameter,     . 
Area  of  heating  surface,    ...... 

Area  of  grate  surface  ( total  of  two  furnaces  ) , 
Area  through  tubes,    .      'V       .        .      ,.       "...  '  '  .'.• 
Height  of  chimney,     .         .        .         .         .         .        r 

Width  of  air  spaces  and  metal  bars  in  grates,  . 
Distance  of  grate  to  shell,          .        .        .        .  • .     * '. 

Distance  of  bridges  to  shell,  .  .  >  .  .-; 
Ratio  of  heating  surface  to  grate  surface,  .  « 
Ratio  of  grate  surface  to  tube  area,  .... 


50 

5-8 
18 

7 


in. 

ft. 


48 
15 
49 

G40       sq.  ft. 
11.7    sq.  ft. 
2       sq.  ft. 

ft. 

in. 

in. 

in. 


54.4   to  1 
5.9   to  1 


BOILEE  No.   18. 
Results  of  Tests,  Boiler  No.  IS. 


121 


Test  No.  52. 

Test  No.  53. 

Bituminous 

Anthracite  Le- 

Cumberland. 

high,   broken. 

Manner  of  start  and  stop  and  kind  of  run,  . 

Ordinary. 

Ordinary. 

Duration,         .        *      "'.        .        .      '  •  lirs. 

10.5 

11 

Coal  consumed,  dry   (including  wood  equiv- 

alent),         Ibs. 

2,368 

1,587 

Percentage  of  asli,      '  •  •.    •     .        .  per  cent. 

8.5 

13.5 

Water  evaporated,        •  ,  '     -._•      .        .  Ibs. 

19,734 

11,496 

Coal  per  hour,         .....  Ibs. 

225.5 

144.3 

Coal  per  hour  per  square  foot  of  grate,   Ibs. 

19.3 

12.5 

Water  per  hour,      Ibs. 

1,879.4 

1,045.1 

Water  per  hour  per  square  foot  of  heating 

surface,     Ibs. 

2.9 

1.6 

Horse-power  developed,        .      .  V      H.  P. 

65.3 

36.3 

Boiler  pressure,       .         .      ;.v;      •  .      •   IDS- 

50.1 

50.9 

Temperature  of  feed-  water,  .     ,  .        •  deg. 

41 

41 

Temperature  of  escaping  gases,    .         .  deg. 

472 

354 

Draught  suction,     .         .         ...     in. 

0.25 

0.12 

Water  per  pound  of  coal,       .        ,:       .  Ibs. 

8.33 

7.24 

Water   per  pound  of  coal  from  and  at  212 

degrees,    Ibs. 

10.00 

8.69 

Water  per  pound  of  combustible  from  and 

at  212  degrees,          .        .                  .   Ibs. 

10.93 

10.05 

The  tests  on  Boiler  No.  18  had  for  an  object  the  determina- 
tion of  the  economy  produced  by  alternate  firing  in  the  double 
furnace  system  which  was  here  employed.  Two  kinds  of  coal 
were  used,  viz  :  Cumberland  coal  on  test  No.  52,  and  anthra- 
cite Lehigh  on  Test  No.  53.  The  Cumberland  coal  gave  an 
evaporation  of  10.93  pounds  of  water  from  and  at  212  degrees 
per  pound  of  combustible,  and  the  boiler  developed  somewhat 
more  than  its  rated  capacity.  This  result  is  much  below  the 
highest  obtained  from  boilers  which  are  set  and  operated  in 
the  usual  manner.  The  cause  of  the  low  performance  may  be 
attributed  in  part  to  the  somewhat  high  degree  of  waste  heat 
escaping  to  the  chimney,  the  temperature  of  the  gases  being  472 
degrees,  though  there  does  not  appear  to  be  a  sufficient  loss  in 
this  alone  to  wholly  account  for  it.  It  is  probable  that  the  use 
of  a  furnace  at  each  end  of  the  boiler,  and  the  arrangement 
of  flues  required  in  this  system,  is  attended  with  a  greater  loss 
from  radiation  than  ordinarily  occurs,  and  that  this  loss  more 
than  offsets  the  advantage  which  might  otherwise  be  obtained 


122  BOILER    TESTS. 

from  the  system.  The  quantity  of  smoke  issuing  from  the 
chimney  with  Cumberland  coal  was  materially  less  than  occurs 
with  the  ordinary  boiler  setting,  and  this  is  an  indication  that 
the  system  exerts  a  favorable  effect  in  securing  more  perfect 
combustion  with  bituminous  coal.  The  test  with  anthracite 
coal  also  gave  a  low  result,  a  fact  which  points  even  more 
plainly  to  the  probability  of  excessive  loss  by  radiation  from 
the  furnace  walls,  as  noted.  Here  the  economy  which  ordi- 
narily attends  a  high  rate  of  combustion  and  low  flue  tempera- 
ture was  not  realized. 

Boiler  No.  19. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used, Four. 

Horse-power  (collective,  basis  12  sq.  feet),  Two  hundred  and  seventy-five. 
Kind  of  coal,  .,* Bituminous,  Cumberland. 

Boiler  No.  19  embraces  four  horizontal  return  tubular 
boilers,  set  in  one  battery  of  brick  work,  the  general  features 
of  which  are  shown  in  the  cuts  of  Boiler  No.  5.  Compared 
with  ordinary  practice,  the  boiler  has  short  tubes  and  large 
grates,  and,  as  a  consequence,  the  ratio  of  heating  surface  to 
grate  surface  is  somewhat  low,  being  29.4  to  1. 

Dimensions  of  Boiler  No.  19. 

Diameter  of  shell, 60      in. 

Length  between  heads  and  length  of  tubes,     .        .        .  12      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,       .     336 

Area  of  heating  surface,  ........  3,534      sq.  ft. 

Area  of  grate  surface,       . '       .        .        ...        .         .     120      sq.  ft. 

Area  through  tubes,  .        .        .        .        .        .        •        •      '••"'  13-8  sq.ft. 

Area  through  flue,      .         .         .        •         .         .        .         .         .       15.9  sq.ft. 

Height  of  chimney,   .        .        .       v  •    •        •        ••      •        •     I23      ft- 

Width  of  air  spaces  and  metal  bars  in  grates,          Air  3-8  in.,  metal  7-16  in. 
Distance  of  grate  to  shell,        .        .        .        ...  .:'"'  .       24      in. 

Distance  of  flat  bridge  to  shell,         .        .        •.        .^   -  ;       ,.         9      in. 
Ratio  of  heating  surface  to  grate  surfaca,       .        .        .        .       29.4  to  1 

Ratio  of  grate  surface  to  tube  area,         ...        .        .         8.7  to  1 

Results  of  Tests,  Boiler  No.  19. 

Test  No.  54. 

Manner  of  start  and  stop,         .•  •      .        .        .        .        .   •     .          Thin  fire. 

Kind  of  run,       .        .        .       /./.      • Continuous. 

Duration,    .        .        .        .....        •        .        .        .       10.2      lirs. 


BOILEE  No.   19.  123 

Coal  consumed,  dry, 13,293  Ibs. 

Percentage  of  ash, .  8.7    percent. 

Water  evaporated, 113,115  Ibs. 

Coal  per  hour, 1,307.6  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .         10.9  Ibs. 

Water  per  hour, 11,125.6  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,         .           3.1  Ibs. 

Horse-power  developed, 380  H.  P. 

Boiler  pressure, 91  Ibs. 

Temperature  of  feed-water,      .        .        .        .        .        .117  deg. 

Temperature  of  escaping  gases, 530  deg. 

Draught  suction, 0.31  in. 

Water  per  pound  of  coal,          ......           8.50  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degress,          .           9.67  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degraes,      10.60  Ibs. 
NOTE.  —  The  coal  when  fired  contained  3  per  cent,  of  moisture. 

The  test  on  Boiler  No.  19  shows  the  performance  of  Cum- 
berland coal  in  boilers  which  were  not  proportioned  and 
operated  in  a  manner  to  give  the  best  results.  The  power  devel- 
oped is  nearly  40  per  cent,  above  the  nominal  capacity.  The 
rate  of  combustion,  though  only  10.9  pounds  per  square  foot  of 
grate  per  hour,  is  high  for  a  boiler  having  the  relatively  small 
amount  of  heating  surface  here  shown.  The  temperature  of 
the  gases  is  excessive,  being  530  degrees.  The  percentage  of 
ash  is  high  for  Cumberland  coal,  and  indicates  some  inferiority 
in  the  quality  of  the  fuel.  The  evaporative  result,  as  might 
be  expected  from  these  unfavorable  conditions,  exhibits  a  low 
degree  of  economy. 

Boilers  No.  2O  and  No.  21. 

Kind  of  boilers, Horizontal  return  tubular. 

Number  used,  each,       .        .        .        .        One. 
Horse-power  each  (basis  12  square  feet  ),  Eighty. 

Kind  of  coal,  each.        .'     .        .        .        .{^gggg**.-* 
Age, No.  20,  two  yrs.,  No.  21,  one  yr. 

Boilers  No.  20  and  21  embrace  two  horizontal  tubular 
boilers  set  in  one  battery  of  brick  work.  They  are  provided 
with  independent  flues  leading  to  the  chimney,  the  arrangement 
of  which  is  shown  in  the  front  elevation  given  in  the  following 
cut.  The  general  arrangement  of  the  brick  setting  of  each 


124 


BOILEE    TESTS. 


boiler  is  the  same  as  that  shown  in  the  cuts  of  Boiler  No.  6. 
The  two  boilers  are  identical,  both  as  to  size  and  general  man- 
ner of  setting,  with  the  exception  that  No.  20  is  provided  with 
perforated  plates  at  the  sides  of  the  furnace  and  top  of  the 
bridge  wall,  for  admitting  air  above  the  fuel,  the  air  first  pass- 
ing back  and  forth  through  ducts  in  the  side  walls.  Boiler 
No.  21  is  provided  with  the  ducts  in  the  same  manner  as  No. 
20,  but  the  entrance  to  these  is  closed,  and  no  outlets  are  pro- 
vided opening  into  the  furnace. 


BOILERS  No.  20  AND  No.  21,  FRONT  ELEVATION. 


Dimensions  of  Boilers  No.  20  and  No.  21. 

Diameter  of  each  shell,     .        .     '    .        .        .        .  .      .        .  60      in. 

Length  between  heads  and  length  of  tubes,     .    •    ..        .        •  15      ft. 

Number  of  tubes  3i  inches  outside  diameter,  .        ;•        •        •  64 

Area  of  heating  surface,   .         .         .        .;.'...         .  959       sq.ft. 

Area  of  grate  surface, 25.8  sq.  ft. 

Area  through  tubes,  .        . 3.7  sq.  ft. 


UNIVERSITY 
-°£CALIFOK.^ 


BOILERS  No.   20  and  No.  21. 


125 


3      sq.  ft. 

Height  of  chimney,   
Width  of  air  spaces  and  metal  bars  in  grates, 

75      ft. 
.      3-8     in. 
26      in. 

Distance  of  flat  bridge  wall  to  shell, 

9      in. 
37.1  to  1 

Ratio  of  errate  surface  to  tube  area, 

7      to  1 

Eesults  of  Tests,  Boilers  No.  20  and  No.  21.     (Average  of  2  runs.  ) 


Boiler  No.  20. 
Test  No.  55. 

Boiler  No.  21. 
Test  No.  56. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

10.5 

10.5 

Coal  consumed,  dry   (including  wood  equiva- 

lent),       Ibs. 

2,842 

3,110 

Percentage  of  ash,       ....  per  cent. 

14.1 

14.5 

20,649 

23,581 

Coal  per  hour,      ......   Ibs. 

270.8 

296.4 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs. 

10.46 

11.46 

Water  per  hour,  Ibs. 

1,967.7 

2,247.3 

Water  per  hour  per  square  foot  of  heating  sur- 

face,         Ibs. 

2.1 

2.3 

Horse-power  developed.      .        .        .         H.  P. 

68.4 

78.7 

Boiler  pressure,    ......   Ibs. 

56.3 

63 

Temperature  of  feed-water,       .        .        .  deg. 

39.5 

39.5 

Temperature  of  escaping  gases,         .        .  deg. 

467 

474 

Draught  suction,          .         .         .         .         .in. 

0.37 

0.39 

Water  per  pound  of  coal,   ....   Ibs. 

7.24 

7.58 

Water   per  pound  of    coal  from  and  at    212 

decrees,         ......  Ibs. 

8.76 

9.17 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  Ibs. 

10.23 

10.74 

NOTE.  —  The  coal  when  fired  contained  3  1-2  per  cent,  of  moisture. 

The  tests  on  Boilers  No.  20  and  No.  21  were  made  to  deter- 
mine the  economy  of  admitting  air  to  the  furnace  over  the  fuel, 
when  using  a  mixture  of  pea  and  dust  and  Cumberland  coal. 
The  two  tests  were  conducted  simultaneously  with  fuel  which 
had  been  thoroughly  mixed  so  as  to  obtain  the  same  quality 
for  both  boilers.  The  evaporative  results  show  that  the  use 
of  air  above  the  fuel,  in  Boiler  No.  20,  was  attended  with  a 
loss  of  4.5  percent,  based  on  coal,  and  4.8  per  cent,  based  on 
combustible.  Boiler  No.  21  was  subsequently  tried  with 
anthracite  broken  coal,  containing  13.3  per  cent,  of  ash,  and 
burning  10.5  pounds  of  coal  per  square  foot  of  grate  per  hour, 
with  a  draught  of  0.29  of  an  inch,  and  gave  an  evaporation  of 


126  BOILER    TESTS. 

11.04  pounds  of  water  per  pound  of  combustible  from  and  at 
212  degrees.  This  is  a  favorable  result  considering  the  tem- 
perature of  the  gases,  which  was  463  degrees. 

Boiler  No.  22. 

Kind  of  boiler,          .        .'       .'  ,     ,'       .        .  Horizontal  return  tubular. 

Number  used,  .......  Two. 

Horse-power  (  collective,  basis  12  square  feet  ),  Two  hundred  and  twenty. 

Kind  of  coal, Anthracite,  Lehigh,  egg. 

Age,          ........  Twelve  years. 

Boiler  No.  22  is  of  the  ordinary  horizontal  tubular  type, 
arranged  and  set  in  the  general  manner  shown  in  the  cuts  of 
Boiler  No.  3.  In  this  case  the  flue  gases  pass  directly  to  the 
chimney,  the  top  of  the  boiler  being  covered  with  brick  work, 
and  the  top  of  the  bridge  wall  is  curved  upward  to  conform  to 
the  curve  of  the  shell.  ,  This  boiler  is  fitted  with  a  much 
smaller  grate  than  is  usually  employed,  and  for  this  reason  the 
proportion  of  heating  surface  to  grate  surface,  which  is  68  to 
1,  is  large,  and  that  of  the  grate  to  tube  area  is  small. 

Dimensions  of  Boiler  No.  22. 

Diameter  of  shell, 60      in. 

Length  between  heads  and  length  of  tubes,     .        .        .  17      ft. 

Number  of  tubes  (  collective)  3  inches  outside  diameter,       .     192 
Area  of  heating  surface,  .','»"••        '        •        .2,680      sq.ft. 
Area  of  grate  surface,       .    ;  - ->-  --    «--*»'        .        *        .•••••••  39      sq.ft. 

Area  through  tubes, 7.9  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          Air  3-8  in.,  metal  7-16  in. 
Ratio  of  heating  surf  ace  to  grate  surface,       .       V-  "•   .        .       68      to  1. 
Ratio  of  grate  surface  to  tube  opening,  .        .        .        •       ,  •         4.9  to  1. 

Eesults  of  Test,  Boiler  No.  22. 

Test  No.  57. 

Manner  of  start  and  stop  and  kind  of  run,     ...'.".,.        .  Ordinary. 

Duration,    .        .        .       '.        .        /      .        .        v        .<        10  hrs. 

Coal  consumed,          ,        .        .        .'-*..'       »        .        .    4,508  Ibs. 

Percentage  of  ash,   '.        .        .    ,  ..  .      . '     ••  *  .     •   .         .         12.9  percent. 

Water  evaporated,      ....-»        .     ••••.        •        •        •        .41,714  Ibs. 

Coal  per  hour,    .        .        .        .        ...        .        .       450.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .        .        .        .         11.5  Ibs. 

Water  per  hour,      '  .>       .        .'"-.,    ....    4,171.4  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,        .           1.6  Ibs. 

Horse-power  developed,    . 124.2  H.  P. 

Boiler  pressure,          •        .        .        .        .        .        .        .         75  Ibs 


BOILEE   No.   22.  127 

Temperature  of  feed  water, 206  cleg. 

Temperature  of  escaping  gases, 350  (leg. 

Water  per  pound  of  coal,          .         ...         .        .        .  9-25  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,  9.62  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  11.03  Ibs. 

The  test  on  Boiler  No.  22  shows  the  performance  of  a  boiler 
having  a  large  proportion  of  heating  surface,  and  using  a 
standard  grade  of  anthracite  coal.  Although  the  amount  of 
power  developed  is  much  below  the  nominal  capacity,  a  reason- 
ably high  rate  of  combustion  is  maintained,  and  the  resulting 
evaporation  of  11.03  pounds  of  water  from  and  at  212  degrees 
per  pound  of  combustible,  is  favorable  when  compared  with 
the  most  economical  work.  This  test  shows  that  a  boiler 
which  is  called  upon  to  do  light  work  can  be  made  to  give 
economical  results  with  a  suitable  adaptation  of  grate  surface. 


Boiler  No.  23. 

Kind  of  boiler,         .        .      ..'••••'     •        •  Horizontal  return  tubular. 

Number  used,    ...        ."        ."        .        *  Three. 

Horse-power  (  collective,  basis  12  square  feet),  Four  hundred  and  fifty. 

Kind  of  coal, .  Anthracite  Chestnut  No.  2. 

Age, Three  months. 

Boiler  No.  23  embraces  a  plant  of  three  horizontal  tubular 
boilers. set  in  one  battery  of  brick  work,  the  general  features 
of  which  are  shown  in  longitudinal  section  in  the  following 
cut.  The  shells  are  72  inches  in  diameter,  and  the  proportion 
of  heating  surface  to  grate  surface  is  much  larger  than  that 
ordinarily  found  in  small  boilers,  being  60  to  1.  In  this 
respect  the  proportions  are  similar  to  those  of  the  double  deck 
type  of  boiler.  The  brick  setting  is  arranged  for  admitting  a 
supply  of  air  at  the  bridge  wall.  Cast  iron  perforated  globes 
are  provided  for  this  purpose  in  the  manner  shown  in  the  cut, 
and  these  receive  air  from  the  outside  through  a  pipe  leading 
to  the  rear  end  of  the  boiler.  A  steam  jet  is  employed  at  the 
end  of  the  pipe  to  increase  the  quantity  of  air  otherwise  sup- 
plied, and  the  steam  mingles  with  the  air  thus  introduced. 


128 


BOILER    TESTS. 


I 


.  _J 


BOILEK  No.  23,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  23. 
Diameter  of  shell,     v.        .  :      . 
Length  between  heads  and  length  of  tubes, 
Number  of  tubes  (  collective)  3 
Area  of  heating  surface,  . 
Area  of  grate  surface, 
Area  through  tubes,  . 
Area  through  flue, 
Height  of  chimney,    . 

Width  of  air  spaces  and  metal  bars  in  grates, 
Distance  of  grate  to  shell, 
Distance  of  flat  bridge  to  shell, 
Ratio  of  heating  surface  to  grate  surface, 
Ratio  of  grate  surface  to  tube  area, 
Ratio  of  grate  surface  to  flue  area, 

Results  of  Test,  Boiler  No.  23. 

Manner  of  start  and  stop  and  kind  of  run,  •  .        i  •  •. 
Duration,    .        >  -      .        .       C*.\'   «        •  -••:' 
Coal  consumed,  dry  (  including  wood  equivalent  ), 
Percentage  of  ash,     .        .        .   -     .        . 
Coal  per  hour,    .        .        .        .  ,     .  •      •  '-,"• 
Coal  per  hour  per  square  foot  of  grate,   . 
Water  per  hour,         .        .        . 
Water  per  hour  per  square  foot  of  heating  surface, 
Horse-power  daveloped,  •  • 


.         .        72 

in, 

f  tubes,     .        .        .                16 

ft. 

les  outside  diameter,         .      420 

5,412 

sq. 

ft. 

.      ,  .         .         .         .90 

sq. 

ft. 

...         .         .        17.3 

sq. 

ft. 

..--..         .         .         .        12.6 

sq. 

ft. 

.       ..         .         .         .        85 

ft. 

in  grates,          .        .        .1-2 

in. 

.        ..         .         .        28 

in. 

.'  •[     ."•...         .        10 

in. 

irface,        ....        60 

to 

1 

pp     '  .        ,   •  '  .     •  ,.   I     5.2 

to 

1 

7.1 

to 

1 

9,901 


Test  No.  58. 
Ordinary. 
10.7  hrs. 

Ibs. 


15.7  per  cent. 


927.9 
.  10.3 
6,979.8 
.  1.3 
241.5 


Ibs. 
Ibs. 
Ibs. 
Ibs. 
H  P. 


BOILER  No.   24.  129 

Boiler  pressure,          »...'•        •        •        •   .  .'  •        •        •  -80  Ibs. 

Temperature  of  feed- water,      .        .  "    »•  '    . '      .        .  .44  deg. 

Temperature  of  escaping  gases,        ,".'-.        .        .  316  deg. 

Draught  suction,         .         .         .-/...         ....    0.32  in. 

Water  per  pound  of  coal,          ..';       .     ;    .        .      '.    -    .  .    7.52  Ibs- 

Water  per  pound  of  coal  from  and  at  212  degrees,          .  .9.10  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  .  10.78  Ibs. 
NOTE.  —  The  coal  when  fired  contained  7  per  cent,  of  moisture. 

The  test  on  Boiler  No.  23  shows  the  performance  of  a  plant 
of  large  boilers  with  one  of  the  small  grades  of  anthracite 
coal.  The  boiler  absorbed  nearly  the  whole  of  the  available 
heat,  and  the  temperature  of  the  waste  gases  was  reduced 
below  that  of  the  water  in  the  boiler.  The  evaporative  result 
secured  is  favorable,  if  account  be  taken  of  the  kind  of  coal 
and  the  moist  condition  in  which  it  was  fired.  The  quantity 
of  power  developed  is  but  little  over  one-half  of  the  rated 
power  of  the  boilers.  Capacity  here  is  sacrificed  for  economy. 
It  is  questionable  whether  the  sacrifice  is  a  wise  one  from  a 
commercial  point  of  view,  for  nearly,  if  not  quite,  as  good 
economy  can  be  obtained  from  boilers  of  smaller  diameter, 
containing  a  less  number  of  tubes,  and  consequently  a  smaller 
amount  of  heating  surface. 


Boiler  No.  24. 

Kind  of  boiler,        %        .       *.       '.       '.        .  Horizontal  return  tubular. 

Number  used,    .        .       ".       '..'..,  One. 

Horse-power  (basis  12  square  feet),      .        ,  Fifty-three. 

Kind  of  coal,    .  /     •  .      »        •        •        •        •  Anthracite  broken. 

Age,  .         .     '.';.  ••    -.         .         .        ,        .  Several  years. 

Boiler  No.  24  is  an  ordinary  horizontal  tubular  boiler, 
arranged  and  set  in  the  same  manner  as  the  return  tubular 
boiler  shown  in  the  cuts  of  Boiler  No.  1,  with  the  exception 
that  the  boiler  under  consideration  has  an  overhanging  front. 
In  this  boiler  the  ratio  of  heating  surface  to  grate  surface  is  too 
small  to  conform  to  the  best  practice.  The  boiler  is  set  only 
17  inches  from  the  grate,  and  the  space  over  the  bridge  wall  is 
contracted  to  a  height  of  4  inches. 


130  BOILER    TESTS. 

Dimensions  of  Boiler  No.  24. 

Diameter  of  shell,       .    •     . 48      in. 

Length  between  heads  and  length  of  tubes,       .  .        .     15      ft. 

Number  of  tubes  3  inches  outside  diameter,      .  .        .        .49 

Area  of  heating  surface,     .        .        .        .        .  .        .        .  639      sq.  ft. 

Area  of  grate  surface,        •   ,.*  •        •        «        .  •        .        .24      sq.ft. 
Area  through  tubes,     ...        ^        .....       2      sq.  ft. 

Area  through  flue,         .        .        ...        .        .  .         .         .       1.3  sq.  ft. 

Height  of  chimney,     ...         .         .        .  .         .         .55      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  .  Air  5-8  in.,  metal  7-8  in. 

Distance  of  grate  to  shell,          .        .       \        .  .       ..        .17      in. 

Distance  of  bridge  wall  to  shell,         .        .        .  .        .        .      4      in. 

Ratio  of  heating  surface  to  grate  surface,         .  .        .        .    26.6  to  1 

Ratio  of  grate  to  tube  area,         .        .        .        .  .  ,     .        .     11.9  to  1 

Eesults  of  Test,  Boiler  No.  24. 

Test  No.  59. 

Manner  of  start  and  stop  and  kind  of  run,      .        .        .        ".         Ordinary. 
Duration,    .        .        .        .        .        ...        .        .        .-        .  11.2  hrs. 

Coal  consumed  (  including  wood  equivalent ),          .  -,     .      2,138  Ibs. 

Percentage  of  ash,     .        .    <    .'       .        .        .        .        .      .  .  12     percent. 

Water  evaporated,      .        .        .        .        ;        .        .        .    18,224  Ibs. 

Coal  per  hour,    .        .        ..    ,  .        .  .        .        .         190  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .        .        .        ,;        »    7.9  Ibs. 

Water  per  hour,          .        .        *        .        .      •  «        .        .      1,619.9  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,        .        .     2.5  Ibs. 

Horse-power  developed, .  48.1        H.  P. 

Boiler  pressure,          .        .        .        .        .     ,- 59  Ibs. 

Temperature  of  feed-water,      .        .        .        .        .       <-.         210.5          deg. 

Temperature  of  escaping  gases,       .        .        .        .        .  •      474  deg. 

Draught  suction,        .         .  '.     .-•      ......     0.30         in. 

Water  per  pound  of  coal,          .......     8.52         Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .        .     8.78         Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,     .     9.87         Ibs. 

The  test  on  Boiler  No.  24  exhibits  the  performance  of  a 
boiler  working  under  unfavorable  conditions  and  giving  a  low 
economic  result.  Here  the  low  rate  of  combustion,  the  high 
temperature  of  the  gases,  and  a  somewhat  large  percentage 
of  ash,  indicate  the  main  cause  of  the  low  degree  of  economy. 
The  large  amount  of  draught  suction  in  the  main  flue,  which 
was  0.3  inches,  is  noticeable  in  view  of  the  fact  that  the  boiler 
worked  to  less  than  its  normal  capacity.  The  reason  for  this 
is  seen  in  the  small  flue  area,  which  was  only  one-eighteenth 
of  the  grate  surface. 


BOILEE  No.   25.  131 

• 

Boiler  No.  25. 

Kind  of  boiler, Horizontal  return  tubutar. 

Number  used, One. 

Horse-power  (  basis  12  square  feet ),      .  Eighty-eight. 

Kind  of  coal, Anthracite  White  Ash  broken. 

Age, Six  months. 

Boiler  No.  25  consists  of  an  ordinary  horizontal  tubular 
boiler  arranged  in  the  general  manner  shown  in  the  cut  of 
Boiler  No.  10.  The  flue  gases,  instead  of  passing  over  the 
top  of  the  shell,  as  there  represented,  proceed  directly  from 
the  smoke  arch  to  the  chimney,  and  the  top  of  the  shell  is 
covered  with  brick.  This  boiler  was  one  of  a  battery  of  two, 
and  the  only  one  in  use. 

Dimensions  of  Boiler  No.  25. 

Diameter  of  shell, »        .  60     in. 

Length  between  heads  and  length  of  tubes,     .                 .        .  16     ft. 

Number  of  tubes  3  inches  outside  diameter,    ....  80 

Area  of  heating  surface,  ........  1,047     sq.  ft. 

Area  of  grate  surface, 23.7  sq.  ft. 

Area  through  tubes,  .........  3.3  sq.  ft. 

Area  through  flue, 4     sq.  f  t. 

Height  of  chimney, .  02     ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          .  Air  5-8  in.,  metal  3-8  in. 

Distance  of  grate  to  shell, 18     in. 

Distance  of  bridge  to  shell, 7     in. 

Katio  of  heating  surface  to  grate  surface,       ....  44.2  to  1. 

Katio  of  grate  surface  to  tube  area, 7.1  to  1. 

Results  of  Test,  Boiler  No.  25. 

Test  No.  60. 
Manner  of  start  and  stop  and  kind  of  run,      .  .        .          Ordinary. 

Duration, 10.5  hrs. 

Coal  consumed  (including  wood  equivalent),          .         .      2,351  Ibs. 

Percentage  of  ash, 15.7  per  cent> 

Water  evaporated, 20,219  Ibs. 

Coal  per  hour,     .         .  .         .         .         .         .         .         223.9  Ibs. 

Coal  per  hour  per  square  foot  of  gra*e, 9.4  ibs. 

Water  per  hour,       . 1,925.6  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,        .        .1.8  Ibs. 

Horse-power  developed, 58.4         H.  P. 

Boiler  pressure,        - 60  ibs. 

Temperature  of  feed-water, 202  deg. 

Temperature  of  escaping  gases,       .....         369  dc?"1. 

Draught  suction, 0.11         in. 


132  BOILER    TESTS. 

Water  per  pound  of  coal, -  8. GO          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .  8.94          Ibs. 

Water  p£r  pound  of  combustible  from  and  at  212  degrees,     .  10.61          Ibs. 

The  test  on  Boiler  No.  25  shows  the  performance  of  a  well 
proportioned  boiler  working  under  favorable  conditions  for 
securing  economy.  There  is  an  ample  amount  of  heating  sur- 
face ;  the  quantity  of  power  developed,  although  small  com- 
pared with  the  nominal  capacity  of  the  boiler,  is  sufficient  to 
secure  a  moderately  high  rate  of  combustion,  and  the  tempera- 
ture of  the  waste  gases  does  not  show  much  loss  of  heat  to  the 
chimney  ;  yet  the  evaporation  per  pound  of  combustible  from 
and  at  212  degrees,  with  a  standard  grade  of  anthracite  coal, 
is  only  10.61  pounds.  The  only  reason  which  can  be  assigned 
for  the  unfavorable  character  of  this  result  appears  to  be  an 
inferior  quality  of  fuel,  which  may  be  inferred  from  the  large 
percentage  of  ash,  this  being  15.7  pel4  cent. 

Boilers  No.  26  and  No.  27. 

Kind  of  boilers,        ..« .      .        .       -I     .  ,.  Horizontal  return  tubular. 

Number  used,  each,  .        .  ,        .  Two. 

Horse-power  (  collective  ),  each  (basis  12 

square  feet),      .       ..       ,.         .         .  Two  hundred  and  eighty. 

Kind  of  coal,      ..".,.    .        .....  ,.-'•  i . •'..  Nova  Scotia  Culm. 

Age,  each,  .        ,        .        ...        ....  Three  months. 

Boilers  No.  26  and  No.  27  are  of  the  ordinary  horizontal  tubu- 
lar type,  and  each  embraces  a  plant  of  two  boilers  set  in  one 
battery  of  brick  work.  They  are  identical  with  respect  to  type, 
arrangement  of  setting,  and  location  with  reference  to  the 

O  O  ' 

chimney,  in  all  respects  except  one :  the  side  walls  of  the  fur- 
naces and  the  top  of  the  bridge  walls  in  Boiler  No.  27  are  pro- 
vided with  perforated  tiles  through  which  air  is  admitted  to  the 
furnaces  above  the  fuel,  while  Boiler  No.  26  has  no  such  pro- 
vision. The  two  batteries  of  boilers  are  located  at  the 
same  distance  from  the  chimney,  one  set  being  on  one  side  of 
the  chimney,  and  one  set  on  the  other  side,  and  a  similar  plan 
is  followed  in  each  case  in  the  arrangement  of  the  flues.  The 
arrangement  of  the  setting  of  the  boilers  is  the  same  in  general 
features  as  that  shown  in  the  longitudinal  section  of  Boiler 


BOILERS  No.  26  and  No.  27. 


133 


No.  6.  These  boilers  are  different,  however,  in  respect  to  the 
arrangement  of  smoke  arches  from  those  shown,  being  pro- 
vided with  flush  fronts.  One  boiler  in  each  battery  has  100 
3£  inch  tubes,  and  the  other  140  3-inch  tubes.  The  total  area 
of  opening  into  the  air  ducts  of  each  battery  is  32  square 
inches.  The  area  of  opening  through  the  registers  of  the  fire 
doors  amounts  to  22  square  inches  for  each  battery. 

Dimensions  of  Boilers  No.  26  and  No.  27. 

Diameter  of  shell,  each,           .......  72     in. 

Length  between  heads  and  length  of  tubes,           .        .        .  16     ft. 

Number  of  tubes  3  inches  outside  diameter,  each,.         .         .  140 

Number  of  tubes  3  1-2  inches  outside  diameter,  each,  .        .  100 

Area  of  heating  surface,  each,       ......  3,347     sq.  ft. 

Area  of  grate  surface,  each, 84     sq.  ft. 

Area  through  tubes,  each,        .......  11.52  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  each,     .         .  3-8    in. 

Distance  of  grate  to  shell,  each, 27     in. 

Distance  of  flat  bridge  to  shell,  each,     .         .         .         .         .  9     in. 

Ratio  of  heating  surface  to  grate  surface,  each,    .         .         .  39.8  to  1 

Ratio  of  grate  to  tube  area,  each, 7.3  to  1 

Results  of  Tests.     Boilers  No.  26  and  No.  27.     (Average  of  two  days). 


Test  No.  61. 
Boiler   No.  26. 

Test  No.  62. 
Boiler   No.  27 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      .......  hrs. 

10.5 

10.5 

Coal  consumed,  dry    (  including   wood  equiva- 

lent),       Ibs. 

12,714 

12,472 

Percentage  of  ash,      ....  per  cent. 

9.4 

9.7 

Water  evaporated,       .....   Ibs. 

91,653 

90,894 

Coal  per  hour,      Ibs. 

1,210.9 

1,187.8 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs. 

14.4 

14.1 

Water  per  hour,  ......  Ibs. 

8,728.9 

8,656.6 

Water  per  hour  per   square   foot  of    heating 

surface,         ......   Ibs. 

2.6 

2.6 

Horse-power  developed,     .        .        .         H.  P. 

298.8 

296.3 

Boiler  pressure,  Ibs. 

79 

79 

Temperature  of  feed-water,       .         .        .  deg. 

57 

57 

Temperature  of  escaping  gases,         .        .  deg. 

528 

513 

Draught  suction,          in. 

0.35 

0.35 

Water  per  pound  of  coal,  .        .        .         .Ibs. 

7.21 

7.28 

Water  per  pound  of  coal  from  and  at  212 

degrees,         Ibs. 

8.65 

8.74 

Water  per  pound  of  combustible  from  and  at 

212  degrees,          Ibs. 

9.51 

9.65 

134  BOILER    TESTS. 

The  tests  on  Boilers  No.  26  and  No.  27  had  for  an  object  the 
determination  of  the  economy  produced  by  admitting  air  above 
the  fuel,  so  far  as  could  be  determined  by  tests  made  on  two 
different  sets  of  boilers.  The  tests  were  conducted  simultan- 
eously and  the  coal  was  used  from  the  same  pile,  previously 
mixed  to  insure  uniformity.  The  registers  in  the  fire-doors 
were  open  in  both  sets  of  boilers. 

The  results  of  the  tests  show  that  the  admission  of  air 
through  the  passages  in  the  walls  increased  the  evaporation 
per  pound  of  coal  one  per  cent.,  and  per  pound  of  combustible 
1 J  per  cent.  This  occurred  with  Nova  Scotia  coal,  which  is 
of  an  extremely  gaseous  and  smoky  character. 

The  results  of  the  tests  as  a  whole  show  a  rather  low 
economy  when  compared,  for  example,  with  the  work  of  Cum- 
berland coal ;  but,  as  a  partial  explanation,  it  is  seen  that  the 
rate  of  combustion  is  large  and  the  temperature  of  the  escap- 
ing gases  is  somewhat  excessive. 

Boilers  No.  28  and  No.  29. 

Kind  of  boilers,.        .  .      .        .        ..        .        Horizontal  return  tubular. 

Number  used,  each,     .        .        .   ;     .        .        One. 

Horse-power,  each  (  basis  12  sq.  ft.  ),        .        No.  28,  150;  No.  29,  130. 

Kind  of  coal,      ......        Nova  Scotia  Culm. 

Age,     ........        Three  months. 

Boilers  No.  28  and  No.  29  are  the  two  horizontal  tubular  boil- 
ers previously  referred  to  as  Boiler  No.  26.  They  are  set  in 
one  battery  of  brick  work,  and  the  style  of  the  setting  is  that 
shown  in  the  cut  of  Boiler  No.  6,  with  the  exception  that  no 
provision  is  made  for  admitting  air  above  the  fuel,  and  the 
boilers  are  provided  with  flush  fronts.  The  two  boilers  are 
duplicates  except  as  to  size  and  number  of  tubes.  In  Boiler 
No.  28  there  are  100  3-inch  tubes,  and  in  Boiler  No.  29  there 
are  100  3^  inch  tubes. 

Dimensions,  Boilers  No.  28  and  No.  29. 

Diameter  of  shell,  each,    .        *        .     '- y        .        •        •  •        72     in. 

Length  of  shell  between  heads  and  length  of  tubes,  each,  .        16     ft. 

Boiler  No.  28.  Boiler  No.  29. 

Number  of  tubes,       .        .        ,:       .,  •    ,    4        140  100 

Outside  diameter  of  tubes,        v -•-  .        .                3     in.  3.5  in. 

Area  of  heating  surface,  ....          1,799     sq.  ft.  1,548     sq.  ft. 


BOILERS  No.  28  and  No.  29. 


135 


Area  of  grate  surface,       .... 

Area  through  tubes, 

Ratio  of  heating  surface  to  grate  surface, 

Ratio  of  grate  surface  to  tube  area, 

Width  of  air  spaces  and  metal  bars  in  grates,  each, 

Distance  of  grate  to  shell,  each, 

Distance  of  flat  bridge  to  shell,  each, 

Results  of  Tests,  Boilers  No.  28  and  No.  29. 


42      sq.  ft. 

42      sq.  ft. 

5.8  sq.  ft. 

5.8  sq.  ft. 

42.8  to  1 

36.8  to  1 

7.3  to  1 

7.3  to  1 

Jh, 

3-8  in. 

. 

27  in. 

•         •         . 

9  in. 

Test  No.  63. 
Boiler  28. 

Test  No.  64. 
Boiler  29. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      hrs. 

10.5 

10.5 

Coal  consumed,    dry    (  including  wood  equiv- 

alent )  Ibs. 

5,5G2 

5,518 

Percentage  of  ash,      ....  per  cent. 

8  5 

9.6 

Water  evaporated,       Ibs. 

41,000 

39,537 

Coal  per  hour,      Ibs. 

521).  7 

525.5 

Coal  per  hour  per  square  foot  of  grate,         Ibs. 

12.6 

12.5 

Water  per  hour,  Ibs. 

3,907.6 

3,705.4 

Water  per  hour  per  square  foot  of  heating  sur- 

face,          Ibs. 

2.2 

2.4 

Horse-power  developed,      ...         H.  P. 

135.8 

129 

Boiler  pressure,  Ibs. 

81 

81 

Temperature  of  feed-water,        .         .         .  deg. 

57 

50 

Temperature  of  escaping  gases,         .        .  cleg. 

489 

480 

Draught  suction,          in. 

0.20 

0.25 

Water  per  pound  of  coal,  ....  Ibs. 

7.49 

7.17 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,    .......  Ibs. 

8.99 

8.00 

Water  per  pound  of  combustible  from  and  at 

212  degrees,           Ibs. 

9.79 

9.49 

The  tests  on  Boilers  No.  28  and  No.  29  had  for  an  object  the 
determination  of  the  effect  which  the  size  of  tubes  has  upon 
the  economy.  This  object  cannot  fairly  be  said  to  have  been 
attained,  because  the  boiler  which  has  the  small  tubes  has  such 
a  large  number  of  them  that  the  heating  surface  is  increased  a 
considerable  amount  above  that  of  the  other  boiler.  The  test 
is  therefore  a  determination  of  the  effect  of  increased  heating 
surface  as  well  as  of  reduced  diameter  of  tubes.  Boiler  No. 
28,  with  the  small  tubes,  gave  the  better  result,  the  increased 
evaporation  being  4.5  per  cent,  based  on  coal,  and  3.2  -^er 
cent,  based  on  combustible. 

It  is  to  be  noted  that  the  temperature  of  the  escaping  gases, 
here  given,  is  highest  in  case  of  the  boiler  with  the  larger  area 
of  heating  surface.  It  is  doubtful  whether  these  figures  indi- 


136 


BOILER   TESTS. 


cate  the  true  temperature.  The  temperature  was  taken  in 
each  case  at  a  point  in  the  main  flue  near  the  smoke  arch,  and 
as  the  flue  was  common  to  both  boilers,  and  both  boilers  were 
in  operation  while  the  test  was  going  on,  it  is  probable  that 
the  temperature  given  is  in  some  degree  an  average  for  both 
boilers,  rather  than  the  actual  temperature  for  the  single  boiler 
tested. 

Boiler    No.  SO. 

Kind  of  boiler,  i  Horizontal  return  tubular. 

Number  used,     ......         One. 

Horse-power  (basis  12  square  feet),        .        Fifty-three. 

Kind  of  coal,      ......        Cumberland  bituminous. 

Age,    .  ......        Several  years. 

Boiler  No.  30  is  an  ordinary  hori- 
zontal tubular  boiler  having  a  special 
arrangement  of  furnace  for  burning 
bituminous  coal.  The  general  feat- 
ures of  the  furnace  and  its  appliances 
are  shown  in  the  following  cuts. 
Several  jets  of  superheated  steam  are 
introduced  beneath  the  grate,  and  a 
supply  of  air  is  forced  in  above  the 
fuel  %  means  of  a  blower.  The 
steam  is  derived  from  the  boiler, 


BOILER  No.  30,  CROSS  SEC- 
TION  THROUGH  FURNACE. 


and  it  receives  its  superheat  from  a  cast  iron  heater  placed  at 
the  back  end  of  the  furnace.  The  quantity  of  steam  used 
amounted  to  about  8  per  cent,  of  the  whole,  and  this  has  been 
deducted  from  the  total  evaporation  to  determine  the  net  quan- 
tities given  in  the  table  of  results. 


BOILER  No.  30,  LONGITUDINAL  SECTION. 


BOILER   No.   30.  137 

Dimensions  of  Boiler  No.  30. 

Diameter  of  shell, 48      in. 

Length  of  shell  between  heads  and  length  of  tubes,        .         .  15      ft. 

Number  of  tubes  3  inches  outside  diameter,    ....  49 

Area  of  heating  surface, 640      sq.  ft. 

Area  of  grate  surface, 13.5  sq.  ft. 

Area  through  tubes,  .........  2      sq.  ft. 

Area  through  flue, •         .  2      sq.  ft. 

Distance  of  grate  to  shell, -.       v.  19      in. 

Distance  of  flat  bridge  to  shell,        .         .         .        .        is     V  6      in. 

llatio  of  heating  surface  to  grate  surface,        .        .        •.       >  47     to  1 

Ratio  of  grate  to  tube  area, 6.6  to  1 

Results  of  Tests,  Boiler  No.  30. 

Test  No.  65. 

Manner  of  start  and  stop, Thin  fire. 

Kind  of  run, Continuous. 

Duration, 7.6  hrs. 

Coal  consumed,  dry, 1,361  Ibs. 

Percentage  of  ash,     .        .         .        .        .        .        .        .         .    0.5  percent. 

Water  evaporated, .      .     10,442  Ibs. 

Coal  per  hour, '      177.9  Ibs. 

Coal  per  hour  per  square  foot  of  grate, 13.2  Ibs. 

Water  per  hour, 1,365  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,         .        .    2.1  Ibs. 

Horse-power  developed, 47.2         H.  P. 

Boiler  pressure,          .........  75  Ibs. 

Temperature  of  feed  water, 44  cleg. 

Temperature  of  escaping  gases,        .         .        .        .        .         362  cleg- 
Water  per  pound  of  coal, 7.67          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .        .9.28          Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,     .    9.91          Ibs. 

The  test  on  Boiler  No.  30  had  for  an  object  the  determina- 
tion of  the  general  performance  of  the  system  of  combustion 
here  employed.  This  system  produced  an  almost  smokeless 
furnace.  A  very  small  quantity  of  light  smoke  appeared  for 
a  short  time  after  firing  fresh  coal,  but  it  was  almost  colorless. 
The  high  character  of  combustion,  which  the  absence  of  smoke 
seemed  to  indicate,  secured  no  apparent  benefit  in  the  matter 
of  economy,  for  after  allowing  for  the  steam  used  by  the 
apparatus,  the  result  is  only  9.91  pounds  of  water  from  and  at 
212  degrees  per  pound  of  combustible,  which  is  some  20 
per  cent,  below  the  best  practice.  This  inferior  performance 
cannot  be  attributed  to  any  unfavorable  conditions  which  the 


138  BOILEE    TESTS. 

test  shows  regarding  the  quality  of  fuel,  rate  of  combustion, 
or  the  temperature  of  the  flue  gases,  for  these  are  such  as 
ordinarily  give  good  results. 

Boiler  No.  31. 

Kind  of  boiler,         -        •        -        •        •        .•  Horizontal  return  tubular. 

Number  used,  ..        .    '.  •  .        ..        ,        .        .  Three. 

Horse  power  (  collective  basis  12  square  feet),  Three  hundred  and  twelve. 

Age,        ,,       u        ..       .        .        .     '  .        .  One  month. 

Boiler  No.  31  consists  of  a  plant  of  three  horizontal  tubular 
boilers,  set  in  one  battery  of  brick  work.  The  general  feat- 
ures of  the  setting  are  similar  to  those  shown  in  the  cut  of 
Boiler  No.  5,  with  the  exception  that  the  bridge  walls  are 
arched  upward  to  conform  to  the  curve  of  the  shell .  These 
boilers  are  deficient  in  flue  area,  this  being  about  one  third  of 
the  area  for  draught  through  the  tubes.  As  a  consequence,  a 
strong  draught  is  required  in  the  flue  to  secure  a  relatively 
slow  rate  of  combustion  and  small  capacity. 

Dimensions  of  Boiler  No.  31. 

Diameter  of  shell,  .        . 66     in. 

Length  between  heads  and  length  of  tubes,           ;  15     ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,    .  306 

Area  of  heating  surface, 3,374     sq.  ft. 

Area  of  grate  surface,    .        .        .        .        .        .        .   i     .  90     sq.  ft. 

Area  through  tubes,         .        .        .        ...        .        .  12.6  sq.  ft. 

Area  through  flue, .-    .  .        .  4.6  sq.  ft. 

Height  of  chimney,         ....  j    .    '    .        .        .  75     ft. 

Width  of  air  spaces  and  metal  bars  in  grates,       .        .        r  1-2    in. 

Distance  of  grate  to  shell,      .        .        ...        .        .       ;«!'  24     in. 

Distance  of  curved  bridge  to  shell,        .        .       -.        .        ..  12     in. 

Ratio  of  heating  surface  to  grate  surface,    .        .        *        .: ',..'     41.6  to  1 

Ratio  of  grate  surf  ace  to  tube  area,       .        .     '   .   ;     .        .  7.1  to  1 

Ratio  of  grate  surface  to  flue  area, 18.3  to  1 


BOILEE  No.  31. 

Results  of  Tests,  Boiler  No.  31. 


139 


Test  No.  66. 

Test  No.  67. 

, 

George's  Creek 
Cumberland. 

Coke  from  gas 
coal. 

Manner  of  start  and  stop,  . 

. 

Thin  fire. 

Thin  fire. 

Factory. 

Factory. 

Duration,     .                          . 

.  hrs. 

11.7 

11.7 

Coal  consumed,  dry, 

.  Ibs. 

7,330 

8,541 

Percentage  of  ash, 

per  cent. 

G.G 

4.9 

Water  evaporated, 

.   Ibs. 

75,119 

79,371 

Coal  per  hour 

.   Ibs. 

G2G.5 

730 

Coal  per  hour  per  square  foot 

of  ijrate, 

"  Ibs. 

7 

8.1 

Water  per  hour,  .... 

.   Ibs. 

6,820.4 

G,  783.8 

Water  per  hour  per  square  foot 

of  heat- 

ing  surface, 

.   Ibs. 

1.8 

1.8 

Horse  power  developed, 

H.  P. 

204.1 

202.9 

Boiler  pressure,  .... 

.  Ibs. 

84 

88 

Temperature  of  feed-water, 

.  deg. 

211 

211 

Temperature  of  escaping  gases, 

.  cleg. 

431 

428 

Draught  suction, 

.    in. 

0.31 

0.2G 

Water  per  pound  of  coal,  . 

.  Ibs. 

10.89 

9.29 

Water  per  pound  of  coal  from  and  at  212 

degrees,         .... 

.   Ibs. 

11.33 

9.GG 

Water  per  pound  of  combustible  from  and 

at  212  degrees, 

.   Ibs. 

12.07 

10.    11 

The  tests  on  Boiler  No.  31  had  for  an  object  the  determina- 
tion of  its  general  economy,  and  the  relative  economy  produced 
with  Cumberland  coal  and  gas  house  coke.  The  evaporative 
result  obtained  with  Cumberland  coal  on  Test  No.  66  compares 
favorably  with  the  best  work.  Although  the  boilers  operated 
under  a  low  rate  of  combustion  and  developed  considerably 
less  than  their  nominal  capacity,  the  flue  gases  passed  off  at  a 
somewhat  high  temperature.  This  may  be  explained  by  the 
fact  of  the  new  condition  of  the  settings  which  prevented 
undue  loss  from  the  admission  of  superfluous  air  through  the 
brick  work.  Comparing  the  results  obtained  with  the  two 
different  fuels,  the  water  evaporated  per  pound  of  coke  is  14.7 
per  cent,  less  than  that  with  the  standard  grade  of  coal.  On 
the  basis  of  prices  which  existed  at  the  time  of  the  tests,  coal 
being  $3.25  per  ton  and  coke  $3.00  per  ton  (  2000  pounds )> 
the  cost  of  coal  required  to  produce  a  given  amount  of  steam 
is  7.4  per  cent,  less  than  the  cost  of  coke. 


140 


BOILER   TESTS. 


Boiler  No.  32. 

Kind  of  boiler,  .        .        .  -     .        . 

Number  used,     .         .        ....        . 

Horse-power  (  collective,  basis  12  sq.  ft.  ), 

Kind  of  coal,     .  ^^. '?.;';       <.  \      . 
Age,    .         .         .         .        .  -.-•-,     .    .         . 


Horizontal  return  tubular. 

Two. 

One  hundred  and  seventy-five. 

George's  Creek  Cumberland. 

Ten  years. 


Boiler  No.  32  embraces  a 
plant  of  two  horizontal  tubu- 
lar boilers,  arranged  in  the 
manner  shown  in  the  follow- 
ing cuts.  The  boilers  are 
set  over  a  single  furnace, 
and  the  upper  surfaces  of  the 
shells  are  exposed  to  the 
heat  of  the  escaping  gases 
on  their  way  from  the  front 
smoke  arch  to  the  flue, 
thereby  furnishing  a  small 
amount  of  steam  heating  sur- 
face. The  boiler  had  been 
in  service  for  several  years, 
but  the  inside  surfaces  were 
free  from  scale,  and  both  boiler  and  settings  were  in  every 
way  in  good  condition.  This  boiler  was  the  end  boiler  of  a 
large  plant,  and  the  boiler  next  to  it  was  in  operation  during 
the  progress  of  the  tests. 


BOILER  No.  32,  LONGITUDINAL  SECTION. 


BOILER  No.  32.  141 

Dimensions  of  Boiler  No.  32. 

Diameter  of  shell, .  54     in. 

Length  between  heads  and  length  of  tubes,     .        .        .        .  15      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,       .  160 

Area  of  water-heating  surface,         .        .        .        .        .  1,080      sq.  ft. 

Area  of  steam-heating  surface, 120      sq.  ft. 

Area  of  total  heating  surface, 2,100      sq.  ft. 

Area  of  grate  surface, 49.3  sq.  ft. 

Area  through  tubes,    .........  6.6  sq.  ft. 

Area  through  flue, 6      sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,        Air  7-16  in.,  metal  5-16  in. 

Distance  of  grate  to  shell,         .         .        .....  19     in. 

Distance  of  flat  bridge  wall  to  shell,         .....  5     in. 

Ratio  of  water-heating  surface  to  grate  surface,    .        .  40     to  1 

Ratio  of  grate  surface  to  tube  area, 7.5  to  1 

Results  of  Tests,  Boiler  No.  32.     (  Average  of  two  ). 

Test  No.  68. 
Manner  of  start  and  stop  and  kind  of  run,      .        .         .        .          Ordinary. 

Duration, 11.5  hrs. 

Coal  consumed,  dry  ( including  wood  equivalent  ),          .      6,288  Ibs. 

Percentage  of  ash,     .         .         .         .  .         .         .  6.5  per  cent. 

Water  evaporated, 58,993  Ibs. 

Coal  per  hour, 546.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .        .        .         .  11.1  Ibs. 

Water  per  hour, 5,134.2  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,          2.6  Ibs. 

Horse-power  developed, 177.6         H.  P. 

Boiler  pressure,          ........  65  Ibs. 

Temperature  of  feed-water, 57  cleg. 

Temperature  of  escaping  gases, 408  deg. 

Draught  suction, 0.35  in. 

Percentage  of  moisture  in  steam,     .        .        .  .  2.2  per  cent. 

Water  per  pound  of  coal, 9.39          Ibs. 

Water  p3r  pound  of  coal  from  and  at  212  degrees,          .  11.20          Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,    .  11.98          Ibs. 

The  test  on  Boiler  No.  32  shows  the  performance  of  an  ordi- 
naiy  tubular  boiler  worked  with  Cumberland  coal.  The  per- 
centage of  ash  is  small  and  indicates  a  good  quality  of  fuel . 
The  rate  of  combustion  is  moderately  high,  and  the  tempera- 
ture of  the  escaping  gases  is  not  excessive  for  bituminous  coal. 
These  conditions  are  favorable  for  economy,  and  the  resulting 
evaporation  bears  out  the  expectations  which  they  justify. 
The  effect  of  the  steam  heating  surface  in  this  boiler  does  not 
appear  to  have  been  sufficient  to  thoroughly  dry  the  steam. 


H2  BOILER   TESTS. 

The  calorimeter  test  showed  that  the  steam  contained  2. 2  per 
cent,  of  moisture.  The  location  of  this  surface  is  favorable 
for  the  deposit  of  soot  and  ashes,  and  it  is  thereby  rendered 
inefficient  for  its  purpose. 

Boiler  No.  33. 

Kind  of  boiler,     .        ..-..-     .        Horizontal  return  tubular. 
Number  used,       .        .        .        .        .        .        Two. 

Horse-power  (collective,  basis  12  sq.  ft.  ),         One  hundred  and  fifty-eight. 

{Two  parts  Anthracite  Lehigh 
Buckwheat,  one  part  Clear- 
field  Bituminous. 
Age,     ........        Five  years. 

Boiler  No.  33  consists  of  a  plant  of  two  horizontal  tubular 
boilers  set  in  one  battery  of  brick  work.  The  general  feat- 
ures of  the  boiler  and  the  style  of  setting  are  similar  to  those 
shown  in  the  cut  of  Boiler  No.  6.  The  boilers  are  fitted  with 
pipes  placed  beneath  the  shell  near  the  side  walls,  and  the  feed 
water  is  first  passed  through  these  pipes.  The  additional  sur- 
face thus  exposed  amounted  to  180  square  feet,  and  this  is 
included  in  the  quantity  given  in  the  table  of  dimensions.  The 
side  walls  and  top  of  the  bridge  wall,  as  shown  in  the  Cut  referred 
to,  are  provided  with  perforated  tiles  for  the  admission  of  air 
above  the  fuel,  and  the  furnaces  are  fitted  with  fire  doors  of 
special  form,  through  which  a  large  amount  of  air  is  also 
admitted.  The  plant  is  provided  with  a  flue  heater  consisting 
of  vertical  cast  iron  pipes,  arranged  in  sections  and  connected 
together  by  means  of  two  headers  placed  outside  the  brick 
work,  one  at  the  lower  end  and  one  at  the  upper  end.  The 
water  supplied  to  the  heater  enters  it  through  the  lower  header 
and  leaves  it  through  the  upper  header.  The  exterior  surfaces 
of  the  pipes  are  kept  clean  by  means  of  scrapers,  worked 
alternately  up  and  down,  and  operated  by  power.  This  is 
placed  in  a  direct  line  between  the  boilers  and  the  chimney, 
as  indicated  in  the  ground  plan  given  in  the  following  cut. 
The  flue,  which  is  provided  for  carrying  the  gases  directly  to 
the  chimney,  lies  beneath  the  chamber  which  encloses  the 
heater.  The  area  of  surface  exposed  to  the  heat  in  this  appar- 
atus is  nearly  as  large  as  the  total  area  of  heating  surface  of 


BOILER  No.   33. 


143 


the  two  boilers.     The  third  boiler  shown  in  the  plan  was  out 


of  use  during  the  tests. 


i^^^^j^^^^^^;^$!^^^<^ 


- 


144 


BOILER   TESTS. 


Dimensions  of  Sailer  No.  33. 

Diameter  of  shell, 60 

Length  between  heads  and  length  of  tubes,  .  .  .  .15 
Number  of  tubes  (  collective  )  3  inches  outside  diameter,  .  132 
Area  of  heating  surf  ace,  .  .  .  .  .  .  «  1,894 


in. 
ft. 


Area  of  grate  surface,       .        .      .  .     „.'.     *  .  /.,. •,',        .        .       50 


sq.  ft. 

sq.  ft. 

Area  through  tubes,  .  5.4  sq.ft. 

Height  of  chimney,    .        .        .                 . .    *  »        .        .        .     no      sq.  ft- 
Width  of  air  spaces  and  metal  bars  in  grates,          Air  3-8  in.,  metal  7-16  in. 
Ratio  of  heating  surface  to  grate  surface,        .        .        .        .'     37.9  to  1 
Ratio  of  grate  surface  to  tube  opening,    .        .        .        .'       .         9.3  to  1 
Area  of  heating  surface  in  flue  heater, 1,600      sq.  ft. 

Results  of  Tests,  Boiler  No.  33. 


Test  No.  69. 

Test  No.  70. 

Heater  in 

Heater  not 

use. 

in  use. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      hrs. 

12 

12 

Coal  consumed,  dry  (including  wood  equiva- 

lent),           '.    •     .  Ibs. 

5,901 

G,564 

Percentage  of  ash,      .        ...     .        •  percent. 

11.8 

11.8 

Water  evaporated,       .        .    •    .        .        .   Ibs. 

51,955 

52*303 

Coal  per  hour,      Ibs. 

491.7 

547 

Coal  per  hour  per  square  foot  of  grate,     .  Ibs. 

9.8 

10.9 

Water  per  hour,  Ibs. 

4,329.5 

4,358.5 

Water  per  hour  per  square  foot  of  heating  sur- 

face,     .......  Ibs. 

2.3 

2.3 

Horse-power  developed,      .        .        .         H.  P. 

145 

146.3 

Boiler  pressure,  ......   Ibs. 

77 

77 

Temperature  of    feed-water  entering  heater, 

deg. 

95 

_ 

Temperature  of  feed-water  entering  boiler,  deg. 

175 

93 

Temperature  of  escaping  gases  leaving  boiler, 

deg. 

346 

399 

Temperature  of  escaping  gases  leaving  heater, 

deg. 

231 

_ 

Water  per  pound  of  coal,  .        .        .        .Ibs. 

8.80 

7.97 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,   .......   Ibs. 

9.22 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  .      -.'."'"'.        .    .-i.        .  Ibs. 

10.45 

NOTE.  — The  coal  when  fired  contained  2 1-2  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  33  were  made  to  determine  the 
economy  produced  by  a  flue  heater  attached  to  ordinary  hori- 
zontal tubular  boilers.  They  have  a  special  interest  in  view 
of  the  fact  that  the  temperature  of  the  escaping  gases  was  not 
above  the  point  which  is  ordinarily  considered  favorable  to 


BOILER  No.  34.  145 

good  results .  The  use  of  the  heater  was  attended  by  a  reduc- 
tion of  115  degrees  in  the  temperature  of  the  gases,  these 
entering  the  heater  at  346  degrees,  and  leaving  it  at. 231 
degrees.  The  temperature  of  the  water  was  raised  from  95  to 
175,  or  80  degrees.  Comparing  the  two  evaporative  results, 
the  water  per  pound  of  coal  was  increased  from  7.97  to  8.80 
pounds,  or  10.5  per  cent.  The  economic  result  produced  when 
the  heater  was  not  in  use,  compares  favorably  with  that 
obtained  in  good  practice,  considering  the  inferior  grade  of 
coal  that  was  employed. 

Boiler  No.  34. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used,      ......        One. 

Horse-power  (basis  12  square  feet),  .         .        Sixty-five. 

Kind  of  coal, Bituminous  Walston. 

Age, Four  years. 

Boiler  No.  34  is  an  ordinary  horizontal  tubular  boiler, 
arranged  and  set  in  the  general  manner  shown  in  the  cut  of 
Boiler  No.  5. 

Dimensions  of  Boiler  No.  34. 

Diameter  of  shell, 54     in. 

Length  between  heads  and  length  of  tubes,    .        .        .         .  12     ft. 

Number  of  tubes  three  inches  outside  diameter,      .         .        .71 

Area  of  heating  surface,  ........  783      sq.  ft. 

Area  of  grate  surface,       .        .        .        .                 .         .         .  24      sq.  ft. 

Area  through  tubes, 2.9  sq.  ft. 

Area  through  flue, 3.1  sq.  ft. 

Height  of  chimney, .        .         .         .  50      ft. 

Width  of  air  spaces  .and  metal  bars  in  grates,       Air  5-16  in.,  metal  1  1-8  in. 

Distance  of  grate  to  shell,        .......  18     in. 

Distance  of  flat  bridge  to  shell,        .        .                 .        .        .  7     in. 

Ratio  of  heating  surface  to  grate  surface,        .        .        .        .  32.2  to  1 

Ratio  of  grate  surface  to  tube  area, 8.3  to  1 

Results  of  Test,  Boiler  No.  34. 

Test  No.  71. 

•  Manner  of  start  and  stop,  /  Ordinary,  with  prelimi- 

).     nary  heating. 

Kind  of  run, Continuous. 

Duration, '  .        .         .         .8.6  hrs. 

Coal  consumed,  dry  (  including  wood  equivalent ),          .      2,5G2  Ibs. 

Percentage  of  ash, 7.3  per  cent. 


146  BOILER   TESTS. 

Water  evaporated,     .     ,v  ....      .  •,>**<>:,?  j>«'^  >:  •*.;•:  •     •    20,395  Ibs. 

Coal  per  hour,    .".",..'•      .        .        .        .        .        ,  ^      .  ;      296  Ibs. 

Coal  per  hour  per  square  foot  of  grate,  .         .        .                    12.3  Ibs. 

Water  per  hour,          .         *-    r. 2,357.7  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,     .            3  Ibs. 

Horse-power  developed,     .  ••*  .  ,  \  ,         .....   .         .         .           79.7  H.  P. 

Boiler  pressure,          .    ''."'*.        .'"''.'     '.        .                   77  Ibs. 

Temperature  of  feed-water,      .         .-       .   '-',   1        .         .           86  deg. 

Temperature  of  escaping  gases,        .         .        .„-     'X'i'V^.v      572  deg. 

Water  per  pound  of  coal,          .        .        .                 .;,r'    .    ,        7.69  Ibs. 

Water  per  pound  of    coal  from  and  at  212  degrees,    .            9.27  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees        10.00  Ibs. 

The  test  on  Boiler  No.  34  shows  the  performance  of  a  hori- 
zontal tubular  boiler,  using  Wallston  bituminous  coal.  This 
fuel  is  a  "  free-burning  "  coal,  similar  in  general  characteristics 
to  that  known  as  Pittsburg  coal.  Judging  from  the  high  tem- 
perature of  the  escaping  gases,  which  was  572  degrees, 
the  area  of  the  heating  surface  does  not  seem  to  have  been 
sufficient  to  attain  the  best  results  from  this  class  of  fuel.  If 
the  loss  from  the  high  temperature  be  measured  by  the  effect 
which  a  liue  heater  would  produce  on  the  economy  under  these 
circumstances,  this  may  be  assumed  to  represent  a  loss  of  at 
least  10  per  cent.  The  performance  with  Wallston  coal,  under 
favorable  conditions,  would  thus  be  an  evaporation  of  about 
11  pounds  of  water  from  and  at  212  degrees  per  pound  of 
combustible.  This  is  about  10  per  cent,  below  the  results  of 
good  practice  for  Cumberland  bituminous  coal. 


Boiler  No.  35. 
Kind  of  boiler,         .....        Horizontal  return  tubular. 

Number  used, Three. 

Horse-power  (  collective  basis  12  sq.  ft.  ),      Two  hundred-and  seventy-five. 
Age, Six  years. 

Boiler  No.  35  embraces  a  plant  of  three  horizontal  tubular 
boilers,  set  in  one  battery  of  brick  work,  the  general  features 
of  which  are  shown  in  longitudinal  section  in  the  following 
cut. 


BOILER  Xo.   35. 


147 


BOILER  No.  35,  LONGITUDINAL,  SECTION. 


Dimensions  of  Boiler  No.  35. 

Diameter  of  shell, 60      in. 

Length  between  heads  and  length  of  tubes,    .        .        .        .  17      ft. 
Number  of  tubes  (  collective,  )  three  inches  outside  diameter,     231 

Area  of  heating  surface, 3,306      sq.  ft. 

Area  of  grate  surface, 69.8  sq.  ft. 

Area  through  tubes, 9.5  sq.  ft. 

Area  through  flue, 10.1  sq.  ft. 

Height  of  chimney, 98      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,         .        .        .  3-8    in. 

Distance  of  grate  to  shell, 19      in. 

Distance  of  flat  bridge  wall  to  shell,      .....  12      in. 

Ratio  of  heating  surface  to  grate  surface,      .         .        .        .  47.4  to  1 

Ratio  of  grate  surface  to  tube  area, 7.3  to  1 


148 


BOILEE   TESTS. 

Results  of  Tests,  Boiler  No.  35. 


Test  No.  72. 

Test  No.  73. 

Kind  of  coal,        .        .        .  -     .         .        .      J 

George's 
Creek 

Philadelphia 
and  Reading 

Cumberland. 

Anthracite 

( 

broken. 

Manner  of    start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      hrs. 

12 

11.7 

Coal  consumed,  dry   (  including  wood  equiva- 

ent),      ...       .   Ibs. 

5,639 

9,765 

Percentage  of  ash,      .        •     .   •  •       .  per  cent. 

8.3 

10.7 

Water  evaporated,       .         .    :'.  "    .        .         .   Ibs. 

50,263 

79,868 

Coal  per  hour,      ......  Ibs. 

469.9 

832.5 

Coal  per  hour  per  square  foot  of  grate,    .   Ibs. 

6.7 

11.9 

Water  per  hour,  Ibs. 

4,204.3 

6,811.6 

Water  per  hour  per  square  foot  of  heating  sur- 

face,      .        .         .        .                 .        .   Ibs. 

1.3 

2.  1 

Horse-power  developed,      .        .        .         H.  P. 

141.3 

228.7 

Boiler  pressure,   ......   Ibs. 

88 

86 

Temperature  of  feed-  water,        .         .        .  dcg. 

94 

96 

Temperature   of  escaping  gases,        .        .  deg. 

340 

428 

Draught  suction,          in. 

0.09 

0.17 

Percentage  of  moisture  in  steam,          per  cent. 

0.86 

0.49 

Water  per  pound  of  coal,    ....   Ibs. 

8.91 

8.18 

Water    per    pound  of    coal  from  and  at  212 

degrees,         .        .        .        .        .        .   Ibs. 

10.34 

9.46 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  .        .      ,  V       v        .        .  Ibs. 

11.24 

10.60 

NOTE.  —  The  Cumberland  coal  when  fired  contained  3  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  35  were  made  to  determine  the  gen- 
eral economy  of  the  boiler  with  Cumberland  and  anthracite 
coal.  The  test  with  Cumberland  coal  was  made  under  condi- 
tions of  a  slow  rate  of  combustion,  and  that  with  anthracite 
coal  under  a  much  higher  rate,  so  that  the  relative  performance 
of  the  two  fuels  cannot  fairly  be  compared.  The  boiler  has 
an  ample  area  of  heating  surface,  the  proportion  of  which  to 
grate  surface  is  47.4  to  1 ;  but  this  does  not  appear  to  have 
been  sufficient  to  absorb  the  whole  of  the  available  heat  which 
was  generated  in  the  case  of  the  test  with  anthracite  coal,  the 
temperature  of  the  escaping  gases  being  428  degrees.  The 
efficiency  of  the  surfaces  had  probably  become  deteriorated  by 
deposits  of  scale,  and  this  furnishes  a  reason  for  the  somewhat 
unfavorable  evaporative  result  which  was  produced.  The 
result  obtained  on  the  test  with  Cumberland  coal  is  equally 
unfavorable,  but  here  the  rate  of  combustion  was  too  low  to 
secure  the  highest  degree  of  economy. 


BOILER   No.   36. 


149 


Boiler  No.  36. 

Kind  of  boiler,      ....        Horizontal  tubular,  cletatched  furnace. 
Number  used,        ....        One. 

Horse-power  (  basis  12  sq.  ft.  ),  .        Two  hundred  and  seventy. 
Age, Two  months. 

Boiler  No.  36  is  a  horizontal 
tubular  boiler  arranged  with  a 
detached  furnace  in  the  gen- 
eral manner  shown  in  longitu- 
dinal section  in  the  following 
cut.  The  position  of  the  fur- 
nace with  reference  to  the 
boiler  is  precisely  that  of  the 
fire-box  of  a  locomotive  boiler. 
After  the  products  of  combus- 
tion have  passed  forward 
through  the  tubes,  they  return 
beneath  the  shell  and  enter  an 
underground  flue  leading  to 
the  chimney.  Direct  radiation 
of  heat  from  the  coal  in  the 
furnace  to  the  tube  sheet  is 
prevented  by  means  of  a  brick 
arch  which  overhangs  the 
grate.  This  boiler  has  a  large 
shell,  long  tubes,  and  a  large 
extent  of  heating  surface  com- 
pared with  grate  surface. 

Dimensions  of  Boiler  No.  36. 

Diameter  of  shell, 96      in. 

Length  between  heads  and  length  of  tubes,  .         .         .  20      ft. 

Number  of  tubes  3  inches  outside  diameter,  .        .        .      200 

Area  of  heating  surface, 3,242        sq.  ft. 

Area  of  grate  surface,    . 56       sq.  ft. 

Area  through  tubes, 8.5    sq.ft. 

Area  through  flue, 0.7    sq.  ft. 

Height  of  chimney, 98      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  Air  3-8  in.,  metal  1-2  in. 
Ratio  of  heating  surface  to  grate  surface,  ....  57.9  to  1 
Ratio  of  grate  surface  to  tube  area, 6.7  to  1  " 


150 


BOILER    TESTS. 
Results  of  Tests.     Boiler  No.   36. 


Test  No.  74. 

Test  No.  75. 

Test  No.  76. 

Test  No.  77. 

Kind  of  fuel,    .        .        .  •! 

Philadel- 
phia and 
ReadingAn- 
thracite 

George's 
Creek 
Cumber- 

lunri 

4  pts.  Geo.'s 
Creek  Cum- 
berland, 6 
pts.  Anthra- 

Crude 
Petroleum. 

\_ 

Manner  of    start  and  stop 

Broken. 

ictnu. 

cite  Screen- 
ings. 

and  kind  of  run,    . 

Ordinary. 

Ordinary. 

Ordinary. 

* 

Duration,       .        .        .  hrs. 

12.4 

10.8 

10.9 

4.6 

Fuel  consumed,  dry  (  includ- 

ing wood    equivalent  )  , 

Ibs. 

8,242 

7,300 

7,450 

2,327 

Percentage  of  ash,  per  cent. 

10.3 

8.3 

8.7 

_ 

Water  evaporated,         .  Ibs. 

72,629 

69,284 

66,671 

28,751 

Fuel  per  hour,        .        .   Ibs. 

665.2 

675.9 

683.5 

504.1 

Fuel  per  hour  per  square  foot 

of  grate,           .         .Ibs. 

11.9 

12.1 

12.2 

_ 

Water  per  hour,    .         .Ibs. 

5,861.5 

6,385.4 

6,102.2 

6,228 

Water  per  hour  per  square 

foot  of  heating  surface, 

Ibs. 

1.8 

2 

1.9 

1.9 

Horse-power  developed,  H.  P. 

196.1 

214.6 

204.8 

209.2 

Boiler  pressure,     .        .   Ibs. 

63 

85 

85 

78 

Temperature  of  feed-water, 

deg. 

94 

95 

96 

93 

Temperature     of     escaping 

gases,      .        .        .  deg. 

321 

397 

367 

429 

Draught  suction,  .         .in. 

0.25 

0.20 

0.31 

_ 

Percentage    of  moisture    in 

steam,     .         .  per  cent. 

- 

0.43 

0.49 

- 

Water  per  pound  of  fuel,  Ibs. 

8.81 

9.49 

8.93  | 

Grossl2.36 
Net     11.80 

Water  per    pound    of    fuel 

from  and  at  212  degrees, 

Ibs. 

10.16 

10.99 

10.33 

Net     13.66 

Water  per  pound  of  combus- 

tible from  and  at  212  de- 

grees,     .        .        .Ibs. 

11.33 

11.99 

11.30 

— 

*  Afternoon  period  of  the  day's  run  starting  with  hot  furnace  and  boiler. 
NOTE.  —  The  Cumberland  coal  when  fired  contained  3  per  cent,  of  moisture  and  the 
mixed  fuel  4  per  cent. 

The  tests  on  Boiler  No.  36  were  made  to  determine  the 
economy  of  this  particular  arrangement  of  setting,  as  also  the 
relative  economy  of  four  different  kinds  of  fuel,  one  of  which 
was  what  is  called  the  "  residuum"  of  crude  petroleum. 
Looking  at  the  individual  results  of  these  tests,  it  appears  that 
the  boiler  showed  a  performance  with  anthracite  coal  which  is 
seldom  exceeded  by  boilers  set  in  the  ordinary  manner.  The 
comparative  result  obtained  with  Cumberland  coal  is  somewhat 
le"ss  favorable,  considering  the  class  of  the  fuel,  though  taken 


BOILER  No.  36.  151 

by  itself  it  represents  excellent  work.  In  view  of  the  new 
condition  of  the  boiler,  however,  these  tests  cannot  be  held  to 
show  special  advantage  due  to  the  use  of  a  detached  furnace. 
Comparing  the  results  of  the  coal  tests  with  each  other,  the 
evaporation  per  pound  of  Cumberland  coal  is  8.1  per  cent, 
greater  than  that  per  pound  of  anthracite  coal ;  and  the  evap- 
oration per  pound  of  the  mixture  is  1  per  cent,  greater. 
Basing  the  comparison  on  the  cost  of  fuel,  the  cost  of  coal 
required  to  produce  a  given  amount  of  steam  is  8  per  cent, 
less  when  Cumberland  coal  is  used,  and  23.5  per  cent,  less 
when  mixed  fuel  is  used,  than  that  of  anthracite  coal.  The 
prices  on  which  these  figures  are  obtained,  per  ton  of  2,240 
pounds,  are  $4.50  each  for  anthracite  and  Cumberland,  and 
$2.75  for  screenings. 

The  apparatus  used  for  supplying  the  petroleum  to  the  fur- 
naces consisted  of  four  injectors,  to  which  the  oil  was  brought 
by  means  of  a  steam  pump.  The  injectors  or  burners  were 
placed  in  a  horizontal  position  in  the  front  wall  of  the  furnace, 
and  pointed  toward  the  middle  of  the  arch.  They  consisted 
of  two  wrought  iron  tubes  one  within  the  other.  The  outer 
one  carried  the  oil,  and  the  inner  one  was  arranged  so  as  to 
supply  a  jet  of  steam,  by  means  of  which  the  oil  was  properly 
distributed  as  it  entered  the  furnace.  The  amount  of  steam 
used  by  the  pump  and  jet  was  4.5  per  cent,  of  that  generated 
by  the  boiler.  After  deducting  this  from  the  total  evapora- 
tion, the  net  amount  of  water  from  and  at  212  degrees  evap- 
orated per  pound  of  oil  was  13.66  pounds.  This  quantity  is 
34  per  cent,  more  than  the  evaporation  per  pound  of  anthra- 
cite coal,  and  24  per  cent,  more  than  the  evaporation  per 
pound  of  Cumberland  coal.  With  Cumberland  coal  at  $4.50 
per  ton  (2,240  pounds),  the  price  of  oil  required  to  make 
the  cost  of  fuel  for  producing  a  given  amount  of  steam  the 
same  in  both  cases,  is  1.8  cents  per  gallon. 

The  result  obtained  with  the  residuum  is  probably  inferior 
to  that  which  would  be  obtained  with  the  crude  oil  itself. 
This  oil  came  from  Pennsylvania.  A  test  made  on  another 
boiler  with  oil  which  was  obtained  from  wells  in  Canada, 


152 


BOILEE    TESTS. 


a  net  evaporation  of  15  pounds  of  water  from  and  at  212 
degrees  per  pound  of  oil.  The  boiler  used  in  this  case  was  of 
the  ordinary  horizontal  tubular  type,'  6  feet  in  diameter  and 
14  feet  long.  It  contained  71  four-inch  tubes,  and  the  ratio 
of  heating  surface  to  grate  surface  was  39  to  1. 

Boiler  No.  37. 

Kind  of  boiler,        .        .        -»        .        .        .  Horizontal  return  tubular. 
Number  used,          .        .        ...        .        .  One. 

Horse-power  (  basis  12  square  feet),  .        .  Ninety-five. 

Kind  of  coal, Bituminous  Ohio  Lump. 

Age,        ........  Several  years. 

Boiler  No.  37  is  an  ordinary  horizontal  tubular  boiler  set  in 
brick  work  in  the  general  manner  shown  in  longitudinal  sec- 
tion in  the  following  cut.  The  fire  door  admits  a  large  amount 
of  air  into  the  furnaces  above  the  fuel,  being  specially  arranged 
for  this  purpose. 


BOILER  No.  37,  LONGITUDINAL  SECTION. 


BOILEE  No.  37.  153 

Dimensions  of  Boiler  No.  37. 

Diameter  of  shell, 72      in. 

Length  between  heads  and  length  of  tubes,     .        .        .        .  14      ft. 

Number  of  tubes,  4  inches  outside  diameter,   .        .        .        .71 

Area  of  heating  surface,  ........  1,144      sq.  ft. 

Area  of  grate  surface,       .         .         .         .  .         .         .  29.2  sq.  ft. 

Area  through  tubes,  .........  5.4  sq.  ft. 

Area  through  flue,      .  7      sq.  ft. 

Height  of  chimney, 60      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  .        .        .  3-8    in. 

Distance  of  grate  to  shell, 24      in. 

Distance  of  curved  bridge  to  shell,. 8      in. 

Ratio  of  heating  surface  to  grate  surface,       .         .        .        .  39.2  to  1 

Ratio  of  grate  surface  to  tube  area, 5.4  to  1 

Eesults  of  Tests,  Boiler  No.  37. 

Test  No,  78. 

Manner  of  start  and  stop j  Ordinary  with  preliminary 

Kind  of  run, Continuous. 

Duration, 9.7  hrs. 

Coal  consumed,  dry  (including  wood  equivalent),          .    3,111  Ibs. 
Percentage  of  ash,     ........           7.6    per  cent. 

Water  evaporated, 22,650  Ibs. 

Coal  per  hour, 319.1  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .         10.9  Ibs. 

Water  per  hour,        ' 2,323.1  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,         .           2  Ibs. 

Horse-power  developed,     .        .        .        .        .        .        .        79.9  H.  P. 

Boiler  pressure, 74.8  Ibs. 

Temperature  of  feed- water, 64.5  cleg. 

Temperature  of  escaping  gases,        .....       501  de»- 

Water  per  pound  of  coal, 7.28  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .           8.64  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,       9.35  Ibs. 

The  test  on  Boiler  No.  37  is  of  interest  in  showing  the  per- 
formance of  Ohio  lump  coal  in  a  horizontal  tubular  boiler. 
There  is  a  noticeably  high  temperature  of  the  escaping  gases, 
this  being  501  degrees,  and  it  may  be  concluded  that  the  boiler 
was  deficient  in  heating  surface.  If  it  had  been  arranged  with 
suitable  proportions,  it  would  doubtless  have  shown  an  evap- 
oration of  10  pounds  of  water  from  and  at  212  degrees  per 
pound  of  combustible,  which  is  16|  per  cent,  below  the  best 
figures  obtained  with  Cumberland  coal.  The  coal  here  used, 
like  that  on  Test  No.  71,  is  what  is  called  "free-burning" 


154 


BOILER    TESTS. 


coal,  and  this  quality  doubtless  has  something  to  do  with  the 
high  flue  temperature. 

Boiler  No.  38. 

Kind  of  boiler.     .        ,  /    »•  •    v  •     .        .     Horizontal  return  tubular. 

Number  used,       .        .,   ,    ••„-••        •        '     One. 

Horse-power  (basis  12  square  feet),          .     Thirty. 

Kind  of  coal,        .       x.        .        .        .        .     Anthracite  Wilkesbarre  broken. 

Age, One  year. 

Boiler  Xo.  38  is  a  horizontal 
tubular  boiler  arranged  for 
superheating  the  steam,  and 
its  general  features  are  shown 
in  the  following  cuts.  The 
steam-heating  surface  is  here 
I  obtained  by  filling  the  steam 
space  above  the  water  line  with 
tubes.  The  products  of  com- 
bustion, after  passing  through 
the  lower  tubes  in  the  usual 
manner,  return  through  the 
superheating  tubes,  and  enter 
the  chimney  from  the  rear  end. 
The  steam  on  leaving  the  boiler 
enters  a  vertical  drum  30 
inches  in  diameter  and  8  feet  high.  The  draft  was  produced 
by  a  blower  which  discharged  under  the  grates. 


BOILEH  38,  LONGITUDINAL  SECTION. 


BOILER  No.  38.  155 

Dimensions  of  Boiler  No.  38. 

Diameter  of  shell, 42  in. 

Length  between  heads  and  length  of  tubes,      ...  10  ft. 
Number  of  tubes,  2  inches  outside  diameter,  below  water-line,  07 
Number  of  tubes,  2  inches  outside  diameter,  above  water-line,    68 

Area  of  water-heating  surface,          .        ,.  ;•  i  ^    ;    .   .     .  369.3  sq.ft. 

Area  of  steam-heating  surface,        „        .    '    .       „;        .  318.8  sq.ft. 

Area  of  grate  surface,        .        .        .        .  •  : ".        .        .  9.2  sq.ft. 

Tube  area  below  water-line,        .       V       .        ...  1.1  sq.ft. 

Flue  area,     .        .        .        .        .        r        •.        •.        •        *.  2.2  sq.ft. 

Height  of  chimney,     .        .        .        .    V,    -    .       ,.  .  -   .  30  ft. 

"Width  of  air  spaces  and  metal  bars  in  grates,  .      ".        .  5-8  in. 

Ratio  of  water-heating  surface  to  grate  surface,      .      '  .    .  40.3  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,       .        .  36.6  to  1 

Ratio  of  grate  surface  to  tube  area  below  water-line,      V?.  8.2  to  1 

Results  of  Tests,  Boil?r  No.  38. 

Test  No.  79. 
Manner  of  start  and  stop,      \ . .  jj|     £    •  gf    .  {  °£e1^  with  Prcliminary 

Kind  of  run,      ,..'...,     ;.       ...      .        .'        .        .'  '  ;  .        .     Continuous. 

Duration,    .        '.....        .        ,.        .        .        .8  hrs. 

Coal  consumed,  (including  wood  equivalent),         .         .    1,453  Ibs. 
Percentage  of  ash,    ...        .        «        .        .        .           9.5    per  cent. 

Water  evaporated,     .    .    .        ,  .      .     .  .        ,.       .        .10,341  Ibs. 

Coal  per  hour, .«    .  ..        .       181.5  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    ....         20  Ibs. 

Water  per  hour,          .         .         .         .         ,                          .    1,291.8  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,     3.5  Ibs. 

Horse-power  developed,    .         .         .,                „"       *        ,         45.5  H.  P. 

Boiler  pressure,          . x      ......        ...        .         66  Ibs. 

Temperature  of  feed-water,      .        .        .       •.        ...         36  cleg. 

Temperature  of  escaping  gases  entering  upper  tubes,     .       558  cleg. 

Temperature  of  escaping  gases  leaving  upper  tubes,       .       394  cleg. 

Number  of  degrees  of  super-heating,       ,,t      .        .     .  ,t       30  deg. 

Water  per  pound  of  coal,          .        .        .        .        ..        ," :        7.12  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,     ."          8.64  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,     9.55  Ibs. 

The  test  on  Boiler  No.  38  shows  the  performance  of  a  super- 
heating boiler  using  anthracite  coal.  The  chief  interest  in  the 
test  lies  in  the  effect  produced  by  the  steam-heating  surface  as 
here  arranged.  The  temperature  of  the  gases  in  passing  over 
this  surface  was  reduced  from  558  degrees,  the  temperature 
on  entering,  to  394  degrees.  This  served  to  dry  the  moisture 
in  the  steam  and  superheat  it  30  degrees  at  the  point  where  it 


156  BOILER    TESTS. 

left  the  drum,  and  probably  50  degrees  at  the  point  of  leaving 
the  boiler.  The  general  results  of  the  test  are  inferior  to  the 
best  boiler  practice.  The  evaporation  per  pound  of  coal, 
however,  is  about  the  same  as  vertical  tubular  boilers  give, 
when  producing  superheated  steam  at  the  same  temperature. 

Boiler  No.  39. 

Kind  of  boiler,      .        .        .        .        .'        .        Horizontal  return  tubular. 
Number  used,        .        .        .        •        •        •        One. 
Horse-power  ( basis  12  square  feet  ),  .         .        Twenty-seven. 
Kind  of  coal,       ..»        .        ••  .     •        .        .        Bituminous  Walston. 
Age, .        .        Several  years. 

Boiler  No.  39  is  an  ordinary  horizontal  boiler  set  in  brick 
work  in  the  general  manner  shown  in  the  cut  of  Boiler  No. 
10,  differing,  however,  from  that  boiler  in  being  provided 
with  an  overhanging  front,  the  gases  from  which  pass  directly 
to  the  chimney.  This  boiler  has  a  small  shell,  short  tubes, 
and  a  low  proportion  of  heating  surface  to  grate  surface. 
Dimensions  of  Boiler  No.-  39. 

Diameter  of  shell, .  42      in. 

Length  between  heads  and  length  of  tubes,     .    •'•'•"       .  .  10      ft. 

Number  of  tubes,  3  inches  outside  diameter,  3G 

Area  of  heating  surface,   .        .        .                 .     :  .        .  .  322      sq.  ft. 

Area  of  grate  surface,       .        .  .      .        .        .             •••  ."  .  14.4  sq.  ft. 

Area  through  tubes,  .         .        .        .         ...,*.  .'  1.5  sq.  ft. 

Area  through  flue,      .         .    -    ,         .         ,        .         .       •..-.:  2.2  sq.  ft. 

Height  of  chimney,    .       -.    '     .        .        *.        .        .        .  .  56      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,      Air  5-16  in.,  metal  11-16  in. 

Distance  of  grate  to  shell,          .        .'.....  „  21     in. 

Distance  of  flat  bridge  to  shell,       '  »       -.        .        .        .        .  8    in. 

Ratio  of  heating  surface  to  grate  surface,        .        .        .  .  22.3  to  1 

Ratio  of  grate  surface  to  tube  area,          .     •  .        .        .  .  9.8  to  1 

Results  of  Test,  Boiler  No.  39. 

Test  No.  80. 

Manner  of  start  and  stop,          .       /      .        _  |  Ordmary^  with  prelimiuary 

Kind  of  run,       ....'.        .        .        .        .  .     Continuous. 

Duration,    .         .  *     .         I         ,r      .        '.         ...  8.3             hrs. 

Coal  consumed,  dry  (  including  wood  equivalent  ),          .  1,134                Ibs. 

Percentage  of  ash,     .        .        .        .        .        .        .        .  7.6    per  cent. 

Water  evaporated,     ..-'..        .        .        .        .  0,519                 Ibs. 

Coal  per  hour.     .        .        . 137.4             Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .  9.52            Ibs. 

Water  per  hour, 1,153.3             Ibs. 


BOILER  No.   40.  157 

Water  per  hour  per  square  foot  of  heating  surface,        .  3.6  Ibs. 

Horse-power  developed, 34.9  H.  P. 

Boiler  pressure, 82.2  Ibs. 

Temperature  of  feed-water, 205.3  deg. 

Temperature  of  escaping  gases, 445  deg. 

Percentage  of  moisture  in  steam, 0.2    per  cent. 

Water  per  pound  of  coal, 8.39  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,           .  8.76  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  9.48  Ibs. 

The  test  on  Boiler  No.  39  shows  the  performance  of  a  small 
horizontal  tubular  boiler  using  Walston  bituminous  coal. 
This  boiler  is  not  one  from  which  to  expect  high  results. 
Being  deficient  in  heating  surface,  a  considerable  loss  occurs 
from  the  heat  of  the  waste  gases,  although  the  rate  of  combus- 
tion is  comparatively  low.  The  result  of  this  test  is  similar, 
though  less  favorable,  to  that  obtained  on  Boiler  No.  34, 
which  used  the  same  kind  of  coal. 

Boiler  No.  4O. 

Kind  of  boiler, Horizontal  return  tubular. 

Number  used, One. 

Horse-power  (  basis  12  square  feet  ),       .        One  hundred  and  five. 
Kind  of  coal,     ......        George's  Creek  Cumberland. 

Age, Several  years. 

Boiler  No.  40  is  of  the  ordinary  horizontal  tubular  type, 
the  general  features  of  which,  and  the  manner  in  which  it  is 
set,  are  shown  in  the  following  cut.  The  setting  is  so  arranged 
that  air  is  supplied  above  the  fuel  in  two  currents,  one  above 
and  one  below  the  burning  gases.  The  first  supply  comes 
from  the  bridge  wall,  which  is  hollow,  and  it  is  discharged 
through  perforations  in  the  rear  face  of  the  wall  near  the  top. 
The  other  current  is  supplied  first  to  a  second  hollow  wall 
placed  a  short  distance  behind  the  bridge  wall,  and  suspended, 
so  to  speak,  from  the  shell  of  the  boiler,  thereby  causing  the 
products  of  combustion  to  pass  beneath  it.  The  air  emerges 
through  perforations  in  the  front  face  of  this  wall  near  the 
bottom. 


158 


BOILEE    TESTS. 


BOILER  No    40,  LONGITUDINAL  SECTION 

Dimensions  of  Boiler  No.  40. 

Diameter  of  shell,      .        .        .        .        .•    * '.        ;     *  .  .       60      in. 

Length  between  heads  and  length  of  tubes,     .     •   .        .  .       17      ft. 

Number  of  tubes,  3J  inches  outside  diameter,  ,  .76 

Area  of  heating  surface,   .        .        .        .        .        .        .  1,262      sq.  ft. 

Area  of  grate  surface,       .        .        ."       .        .        .        ,  .       23.7  sq.ft. 

Area  through  tubes,    .        .        .      *.'••».       .    .    ..        .  .         4.4  sq.ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          .  Air  1-2  in.,  metal  3-8  in. 
Distance  of  grate  to  shell,        .        .        .        ......       24      in. 

Distance  of  flat  bridge  to  shell,        .    .    .       v     ...        .  .         9      in. 

Ratio  of  heating  surface  to  grate  surface,       .        .     .   .  .       53.1  to  1 

Ratio  of  grate  surf  ace  to  tube  area,      '..,..     .  .        .  .     .   5.4  to  1 

Results  of  Test,  Boiler  No.  40. 

Test  No.  81. 

(  Ordinary,  with  preliminary 
*  \     heating. 

.      i.  '....«•.      ..'.*"     .        .     Continuous. 
,.-..  '.%    ..     ,..     ...  ".'.V,,       9.7 
.,      ^       -.       ..        ,       '..    3,149 

.-'   .  .  -.,-    .•••^;  ••  •-.      .  7.5 

.         .         *,  5     .'      i         .34,116 

323 


Manner  of  start  and  stop, 

Kind  of  run,       .  . 

Duration,    .        .  . 

Coal  per  hour,     .  . 

Percentage  of  ash,  .    . 

Water  evaporated,  .     » 

Coal  per  hour,     .  . 


Coal  per  hour  per  square  foot  of  grate,    .        .        .  .  13.6 

Water  per  hour,          .       ".      '  .        .    *    .        .        .  .  3,499.4 

Water  per  hour  per  square  foot  of  heating  surface,  .  .  2.8 

Horse-power  developed,     .      •„  ^     .        .        .        .  .  108.1 

Boiler  pressure,          .      ,.     .   .       \        ..       .        .  .  61.7 

Temperature  of  feed-  water,      „        .        .        .        .  .  178.7 

Temperature  of  escaping  gases,        .        .        .        .  .  413 

Draught  suction,        .        .        •      -•        '        •        •  •  0.15 

Water  per  pound  of  coal,          .        .        .        .        .  .  10.83 

Water  per  pound  of  coal  from  and  at  212  degrees,  .  11.54 
Water  per  pound  of  combustible  from  and  at  212  degrees,      12.47 


hrs. 
Ibs. 

percent. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
H.  P. 
Ibs. 
deg. 
deg. 
in. 
Ibs. 
Ibs. 
Ibs. 


BOILER  No.   40. 


159. 


The  test  on  Boiler  No.  40  shows  the  performance  of  a  hori- 
zontal tubular  boiler  using  Cumberland  bituminous  coal.  The 
conditions  under  which  this  test  was  made  are  all  favorable  to 
the  production  of  a  high  result,  and  the  desired  end  was 
realized  in  a  notable  degree,  the  evaporation  being  12.47 
pounds  from  and  at  212  degrees  per  pound  of  combustible. 
The  ratio  of  heating  surface  to  grate  surface  is  ample,  being 
53.1  to  1,  the  coal  was  burned  at  a  sufficient  rate  for  good 
combustion,  a  supply  0f  air  was  introduced  above  the  fuel  in 
such  a  way  as  to  thoroughly  mix  with  the  burning  gases,  and  the 
heat  wasted  at  the  chimney  was  noticeably  small  for  bitumi- 
nous coal.  The  character  of  the  combustion,  as  viewed 
through  a  peek-hole  at  the  back  end  of  the  boiler,  was  excel- 
lent, and  the  appearance  of  the  brick  work  at  the  rear  part  of 
the  setting  indicated  a  high  degree  of  heat.  There  was  a 
marked  absence  of  dense  black  smoke  discharged  from  the 
chimney. 


Boiler  No.  41. 


Kind  of  boiler,  .... 

Number  used,     .        .        .        .    '    . 
Horse-power  (  basis  15  square  feet  ), 
Kind  of  coal,      .        .        .        . 
Age,    .        .        .        . 

Boiler  No.  41  is  a  so- 
called  "  d  o  u  b,  1  e-d  e  c  k  " 
boiler,  arranged  and  set 
in  the  manner  shown  in 
the  following  cuts.  It 
differs  from  the  ordinary 
form  of  horizontal  return 
tubular  boiler  in  having 
two  connecting  shells,  one 
above  the  other.  The 
lower  shell  is  completely 
filled  with  tubes.  The 
upper  shell  is  provided 
simply  to  furnish  steam 


"  Double-deck,  "  hor.  ret.  tub. 

One. 

Eighty-five. 

Bituminous  Cumberland. 

One  month. 


160 


BOILER    TESTS. 


room,  and  the  water  line  is  carried  up  to  about  the  middle 
point  in  this  shell.  The  area  of  heating  surface  for  a  given 
amount  of  grate  surface,  and  the  area  through  the  tubes,  is 
much  larger  in  this  form  of  boiler  than  in  the  ordinary  type. 
In  this  respect  the  boiler,  from  an  engineering  point  of  view, 
possesses  its  chief  characteristic.  The  brick  setting  is  arched 
over  the  top  of  the  drum,  as  shown  in  the  cut,  and  the  whole 
of  the  shell  is  exposed  to  the  heat  of  the  escaping  gases  on 
their  way  to  the  chimney.  The  boiler  is  thus  provided  with  a 
small  amount  of  steam-heating  surface. 


BOILER  No.  41,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  41. 

Diameter  of  lower  shell,  .  .  .,.  .  •  ;  •  •  •  54 
Diameter  of  upper  shell,  .  >  x  .  .  .  .  •  •  32 
Length  of  shells  and  tubes,  .  .  »v.  .  i  .  -  .12 

Number  of  tubes  (3  inches  diameter), 118 

Area  of  water-heating  surface,         ...         .         •         •  1,221 

Area  of  steam-heating  surface,        .        .        .        •        •        .60 

Area  of  grate  surface, 20 

Area  through  tubes, •        •        •         4- 

Ratio  of  water-heating  surface  to  grate,  .  .  .  .61 
Ratio  of  steam-heating  surface  to  grate,  .  .  .  •  8 
Ratio  of  grate  to  tube  area, * 


in. 
in. 
ft. 

sq.  ft. 

sq.  ft. 

sq.  ft. 
9  sq.  ft. 

to  1 

to  1 
1  to  1 


BOILER  No.  41.  161 

Results  of  Tests,  Boiler  No.  41. 

Test  No.  82. 
Manner  of  start  and  stop,         .        ;.--..•      .       ••'.        .        .          Running. 


«                  12 

hrs 

Coal  consumed,  .        .        .        .        .        .        . 
Percentage  of  ash,     .        . 
Water  evaporated,      .        .        .        .     _  . 
Coal  per  hour,     
Coal  per  hour  per  scmare  foot  of  grate,    . 

.    1,912 
•                     7 

...  '       .  19,991 
159.3 
.  7  96 

Ibs. 
per  cent. 
Ibs. 
Ibs. 
Ibs 

Water  per  hour,          .        ...        .• 
Water  per  hour  per  square  foot  of  water-heating 
Horse-power  developed,     .        ;  '     . 
Boiler-pressure,          ...        . 

.         .    1,665.9 
surface,        1.36 
50.4 

.:       81 

Ibs. 
Ibs. 
H.  P. 

Ibs 

Temperature  of  feed-water,      ,        ,        .       •. 

197 

(1  go- 

Temperature  of  escaping  gases, 

322 

05 

cleg, 
per  cent 

Water  per  pound  of  coal,           .        .        .        . 
Water  per  pound  of  coal  from  and  at  212  degrees 
Water  per  pound  of  combustible  from  and  at  212 

10.45 
10.98 
degrees,      11.81 

Ibs. 
Ibs. 
Ibs. 

The  results  of  the  test  on  Boiler  No.  41  are  of  interest  in 
showing  the  effect  produced  by  the  large  extent  of  heating 
surface  which  the  double-deck  type  of  boiler  contains.  The 
evaporation  per  pound  of  combustible  from  and  at  2 1 2  degrees , 
which  is  11.81,  is  higher  than  that  obtained  from  some  hori- 
zontal return  tubular  boilers  of  the  ordinary  kind ;  but  at  the 
same  time,  it  is  inferior  to  the  best  results  from  those  boilers. 
The  rate  of  combustion,  which  is  7.96  pounds  per  square  foot 
of  grate  per  hour,  is  probably  too  low  for  the  best  results  on 
a  boiler  having  such  a  large  amount  of  heating  surface,  and 
the  conditions  of  the  tests  are  not  in  this  respect  the  most 
favorable.  Taking  into  account  simply  the  evaporative  result, 
it  would  appear  that  the  increased  surface  over  a  well  arranged 
return  tubular  boiler  of  the  ordinary  type,  produced  no  mate- 
rial benefit.  That  the  large  area  of  heating  surface  was 
efficient  in  absorbing  the  heat  is  seen  in  the  low  temperature 
of  the  escaping  gases,  which  was  322  degrees,  this  being  below 
the  temperature  of  the  water  in  the  boiler.  The  steam  which 
the*  boiler  generated  contained  0.5  of  one  per  cent,  of  moisture 
as  indicated  by  a  barrel  calorimeter.  From  this  it  appears 
that  the  steam-heating  surface  in  the  upper  shell  was  not  suffi- 


162 


BOILER   TESTS. 


cient  to  superheat  the  steam,  although  it  may  have  acted  fav- 
orably in  reducing  the  amount  of  moisture  present  to  the  low 
figure  named. 

Boiler  No.  42. 

Kind  of  boiler,          .        »     '   .        .        .        .     "  Double-deck  "hor.  ret.  tub. 
Number  used,  .        .        .        .        .  •      .    -    .    Three. 
Horse-power  (  collective,  basis  15  square  feet  ),  Three  hundred  and  ninety. 
Age, ».,.<•    New. 

Boiler  No.  42  embraces  a  plant  of  three  60-inch  "  double- 
deck  "  boilers  set  in  one  battery  of  brick-work,  as  indicated  in 
cross  section  in  the  following  cut.  The  longitudinal  section  is 
of  the  same  general  form  as  that  shown  in  the  cut  of  Boiler 
No.  41.  This  boiler,  like  the  preceding  one,  has  a  much 
larger  area  of  heating  surface  and  tube  area  for  a  given  size  of 
grate  than  the  ordinary  tubular  boiler,  and  this  is  its  character- 
istic feature. 


BOILER  No.  42,  CROSS  SECTION  THROUGH  FURNACES. 

Dimensions  of  Boiler  No.  42. 

Diameter  of  lower  shell,  . /-••    .  ••/•  . 60 

Diameter  of  upper  shell,  .  •  '[ .  J,  -  .'"  *  .  .  .  .  .  34 
Length  of  shell  and  tubes,  ,.'.-.  .  .  .  .15 
Number  of  tubes  (  collective  )  3  inches  outside  diameter,  .  420 

Area  of  water-heating  surface, 5,850 

Area  of  steam-heating  surface, 300 


in. 
in. 

ft.  . 

sq.  ft. 
sq.  ft. 


BOILER  No.   42. 


163 


Area  of  grate  surface, 90     sq.  ft. 

Area  through  tubes, 17.3  sq.  ft. 

Area  through  chimney, 11.1  sq.  ft. 


Height  of  chimney, 

Katio  of  water-heating  surface  to  grate  surface, 
Ratio  of  steam-heating  surface  to  grate  surface, 
Ratio  of  grate  to  tube  area,       .... 
Ratio  of  grate  to  chimney  area, 


100      ft. 

65      to  1 

3.3  to  1 

5.2  to  1 

8.1  to  1 


Results  of  Tests,  Boiler  No.  42,  (Average  of  three.) 


Test  No.  83. 

Test  No.  84. 

Anthracite 

Bituminous, 

Lackawan- 

Geo.'s  Creek 

na,    Broken. 

Cumberland. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,     .......  hrs. 

12 

11.8    . 

Coal  consumed,  dry   (including  wood  equiva- 

lent),            Ibs. 

15,385 

11,646 

Percentage  of  ash,       .        .        .        .  per  cent. 

12.3 

6.7 

Water  evaporated,       Ibs. 

141,574 

129,348 

Coal  per  hour,      Ibs. 

1,282.1 

987 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs. 

14.25 

10.97 

"Water  per  hour,  Ibs. 

11,797.8 

10,961.7 

Water  per  hour  per  square  foot  of  water-heat- 

ing surface,            .....   Ibs. 

2.02 

1.87 

Horse-power  developed.      .        .        .         H.  P. 

359 

331.8 

Boiler  pressure,    Ibs. 

82.5 

81.7 

Temperature  of  feed-water,        .        .        .  deg. 

199.3 

205 

Temperature  of  escaping  gases,         .        .  deg. 

392 

389 

Percentage  of  moisture  in  steam,       .  per  cent. 

_ 

0.5 

Water  per  pound  of  coal,   .        .        .        .Ibs. 

9.20 

11.08 

Water  per  pound  of    coal  from  and  at    212 

degrees,         ......  Ibs 

9.65 

11.55 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  Ibs. 

11.11 

12.42 

The  tests  on  Boiler  No.  42  were  made  in  the  same  series  as 
those  of  Boiler  No.  3,  one  set  of  boilers  being  used  when  the 
other  set  was  idle,  and  both  being  employed  for  the  same  work. 
A  comparison  of  Tests  No.  5  and  No.  83  may  be  made  to  show 
the  efficiency  of  the  two  types  of  boilers.  Both  tests  were 
made  with  coal  from  the  same  cargo.  The  double-deck  boiler 
secured  a  somewhat  better  result  than  the  common  boiler,  the 
figures  per  pound  of  combustible  being  11.11  and  10.73. 
The  difference  is  3.5  per  cent.  The  reason  for  this  result  is 
seen  in  the  reduced  quantity  of  waste  heat.  The  temperature 

^f^t'        OT 
UNIVERSITY  1 

. 


164  BOILER   TESTS. 

of  the  escaping  gases  in  the  two  cases  is  482  degrees  and  392 
degrees,  respectively.  The  reduction  is  evidently  due  in  a 
measure  to  the  increased  amount  of  heating  surface  which  the 
double-deck  boiler  provides.  There  is  5,850  square  feet  of 
surface  in  this  boiler,  against  only  4,056  square  feet  in  the 
common  boilers.  While  an  improvement  might  be  expected 
from  this  cause,  the  whole  of  the  improvement  cannot  be  attri- 
buted to  the  difference  in  the  type  of  boiler,  because  the 
double-deck  boilers  were  new  and  clean,  while  the  common 
boilers  were  old  and  presumably  somewhat  inefficient  from 
long  usage.  It  is  quite  probable  that  the  whole  of  this  small 
improvement  (which,  as  noted,  is  only  3.5  per  cent.  )  maybe 
attributed  to  the  difference  in  age  and  condition  of  the  heating 
surfaces,  rather  than  to  the  change  in  the  type  of  boiler. 

The  results  of  Tests  No.  83  and  No.  84  may  be  compared  to 
show  the  relative  economy  of  Lacka wanna  coal,  broken  size, 
and  George's  Creek  Cumberland  coal.  The  bituminous  coal, 
considered  by  itself,  gave  exceptionally  good  results.  The 
large  draught  area  through  the  tubes  appears  to  be  a  favorable 
condition  in  cases  like  this,  where  the  gaseous  element  of  com- 
bustion forms  so  prominent  a  feature.  If  this  be  so,  the  com- 
parison between  the  economy  of  the  two  fuels  shows  a  larger 
difference  in  favor  of  the  bituminous  coal  than  would  be  shown 
on  some  different  type  of  boiler.  Taking  the  figures  as  they 
stand,  however,  there  is  a  difference  of  11.55  —  9.65  = 
1.90  pounds  of  water  in  favor  of  the  performance  of  the 
bituminous  coal,  which  is  a  gain  of  nearly  20  per  cent,  over 
that  of  the  anthracite  coal,  and  this  gain  represents  a  saving 
in  the  quantity  of  bituminous  coal  required  to  do  a  given 
amount  of  work  of  16.4  per  cent. 

In  comparing  the  two  kinds  of  fuel  used  on  Tests  No.  83  and 
No.  84,  a  marked  difference  is  to  be  observed  in  the  quantity 
of  ash.  The  percentage  of  ash  in  the  anthracite  coal  is  12.3 
per  cent,  and  that  in  the  bituminous  coal  6.7  per  cent. 


BOILEE   No.   43. 


105 


Boiler  No.  43. 

Kind  of  boiler, "  Double-deck"  hor.  ret.  tub. 

Number  used,  One. 


One  hundred. 

New. 


Horse-power  (  basis  15  square  feet ) , 
Age, 

Boiler  No.  43  is  of  the 
double-deck  type  having  the 
general  features  shown  in  the 
following  cuts.  It  has  two 

o 

shells,  one  completely  filled 
with  tubes  and  the  other  serv- 
ing principally  as  a  steam 
drum.  The  brick  setting  is 
arranged  so  as  to  admit  air 
through  the  perforations  in 
the  side  walls  at  the  back  end 
of  the  furnace  and  perforations 
in  the  top  of  the  bridge  wall. 
The  air  supplied  in  this  man- 
ner is  first  passed  through  BOILER  Na  43>  CROSS 
ducts  extending  back  and  forth  THROUGH  FURNACE. 

through  the  walls,  whereby  it  is  to  somo  extent  heated 


SECTION 


BOILER  No.  43,  LONGITUDINAL,  SECTION. 


166 


BOILEE    TESTS. 


Dimensions  of  Boiler  No.  43. 
Diameter  of  lower  shell,  .        .        .        . ' '""  ". 

Diameter  of  upper  shell,  . 

Length  of  shell  and  tubes,       • .        .       - .        .      . » 
Number  of  tubes  3  inches  outside  diameter,     . 
Area  of  water-heating  surface,         .         .        . 
Area  of  steam-heating  surface,         .... 

Area  of  grate  surface,       .        .        .        . 

Area  through  tubes,  ....... 

Area  through  chimney,      ...... 

Height  of  chimney, A. 

Width  of  air  spaces  and  metal  bars  in  grates, 
Ratio  of  water-heating  surface  to  grate  surface, 
Ratio  of  steam-heating  surface  to  grate  surface,     . 
Ratio  of  grate  surface  to  tube  area, 

Results  of  Tests,  Boiler  No.  43. 


.  1 


54 
36 
15 
114 
521 
88 
22.5 
9.4 
7.1 
70 
3-8 
67.6 
3.9 
4.8 


in. 
in. 
ft. 

sq.  ft. 
sq.  ft. 
sq.  ft. 
sq.  ft. 
sq.  ft. 
ft. 
in. 
to  1 
to  1 
to  1 


Test  No.  85.    Test  No.  86.    Test  No.  87.  I  Test  No.  88. 

I 


Kind  of  fuel,    .        .      -j 

Manner  of  start  and  stop 
and  kind  of  run, 

Duration,          .        .  hrs. 

Coal  consumed,  dry  (  in- 
cluding wood  equiva- 
lent, )  .  .  Ibs. 

Percentage  of  ash, 
per  cent. 

Water  evaporated,      Ibs. 

Coal  per  hour,          .  Ibs. 

Coal  per  hour  per  square 
foot  of  grate,  .  Ibs. 

Water  per  hour,        .   Ibs. 

Water  per  hour  per  square 
foot  of  water-heating 
surface,  .  .Ibs. 

Horse-power  developed, 
H.  P. 

Boiler  pressure,        .  Ibs. 

Temperature  of  feed- 
water,  .  .  deg. 

Temperature  of  escaping 
gases,  .  .  deg. 

Moisture  in  steam  by  cal- 
orimeter, per  cent. 

Water  per  pound  of  coal, 
Ibs. 

Water  per  pound  of  coal 
from  and  at  212  de- 
grees, .  .Ibs. 

Water  per  pound  of  com- 
bustible from  and  at 
212  degrees,  .  Ibs. 


Mixture  1  pt. 

Nova  Scotia 

Culm,  3  pts. 

Pea  and 

Dust. 

Av.  3  days. 
Ordinary. 
11.5 


2,983 

14.7 
24,671 
259.3 

11.5 
2,145 


1.4 

64.3 
75.3 

206 
339 
1.2 

8.27 

8.59 
10.07 


Delaware 
and  Lacka- 
wanna  Brok 
en  Anthra- 
cite. 

Av.  2  clays. 
Ordinary. 
11.5 


2,485 

15.5 
21,091 
216.1 

9.4 
1,834 


1.2 

55 
74 

211 
335 

8.48 

8.78 

10.39 


George's 
Creek    Cum- 
berland 
Bituminous. 

Av.  2  days. 
Ordinary. 
11.5 


2,131 

6.7 

21,137 
185.4 

8.2 
1,838 


1.2 

55 
74.2 

211 

348 


9.92 
10.26 
10.99 


Nova  Scotia 
Culm. 


One  day. 
Ordinary. 
9.5 


2,390 

10.4 
18,938 
247.7 

11.2 
1,994 


1.3 

59.8 
71.7 

210 
348 


7.93 

8.21 
9.19 


NOTE.  — The  coals  when  fired  contained  tho  following    percentages  of  moisture: 
Mixed  fuel,  G  per  cent. ;  Cumberland,  2.5  per  cent. ;  Nova  Scotia  Culm,  7  per  cent. 


BOILER  No.  43. 


167 


The  tests  on  Boiler  No.  43  embrace  a  series  made  to  deter- 
mine the  relative  economy  of  different  kinds  of  coal.  The 
best  evaporative  result  was  obtained  with  George's  Creek 
Cumberland  coal,  this  being  10.26  pounds  of  water  from  and 
at  212  degrees  per  pound  of  coal.  Compared  with  the  other 
results  this  is  17  per  cent,  better  than  that  obtained  with 
anthracite  coal,  19  per  cent,  better  than  that  given  by  the 
mixed  coal,  and  25  per  cent,  better  than  that  given  by 
the  Nova  Scotia  culm.  Based  on  the  cost  of  fuel  required  to 
produce  one  day's  supply  of  steam,  say  30,000  pounds  from  and 
at  212  degrees,  using  the  prices  of  coal  which  ruled  at  the 
time  of  the  tests,  the  various  results  are  as  follows : 


Mixture,  Pea 

Delaware 

George's 

Nova 

and  Dust  3 

and  Lacka- 

Creek  Cum- 

Scotia Culm. 

parts,    Nova 

wanna  An- 

berland 

Scotia   Culm 

thracite 

Bituminous. 

l  part. 

Broken. 

Costof  2,  240  pounds  coal, 

$4  02 

$5  90 

ft  6  75 

$3  80 

Cost  of    coal  for  30,000 

pounds  steam,    . 

6  31 

9  18 

8  91 

7  14 

1 

From  these  figures  it  is  seen  that  the  best  result  in  point  of 
cost  of  fuel  was  obtained  with  the  mixed  fuel,  and  this  is 
represented  by  an  expenditure  of  $6.31  per  day.  Comparing 
the  best  grades  of  coal  which  were  tested,  viz  :  the  Anthracite 
and  Cumberland,  it  appears  that  the  highest  priced  coal  per 
ton,  that  is,  the  Cumberland,  owing  to  its  better  evaporative 
performance,  was  in  reality  the  cheapest,  the  cost  per  day's 
run  being  $0.27  less  than  that  of  anthracite  coal. 

During  Test  No.  86  the  air  passages  in  the  walls  were  closed 
and  no  air  entered  the  furnace  above  the  fuel  except  that 
which  found  its  way  through  cracks  in  the  setting,  and  through 
the  registers  in  the  fire  door. 

During  one  day's  run  on  Test  No.  87,  which  was  made  with 
Cumberland  coal,  the  coal  was  wet  after  being  weighed,  the 
amount  of  water  used  being  5  per  cent,  of  the  weight  of  the 
coal.  On  the  day  when  the  coal  was  wet,  the  quantity  of 
water  evaporated  by  the  boiler  with  the  same  weight  of  dry 
coal,  was  increased  3  per  cent. 


168  BOILER    TESTS. 

The  individual  results  of  the  tests  made  with  the  standard 
grades  of  coal,  viz :  Tests  No.  86  and  No.  87,  are  not  so  high 
as  the  best  obtained  from  other  boilers  of  similar  type. 
Boiler  No.  41  with  Cumberland  coal  gave  an  evaporation  per 
pound  of  combustible  from  and  at  212  degrees  of  11.81 
pounds,  and  Boiler  No.  42  with  similar  coal,  gave  12.42 
pounds.  The  last  named  boiler  with  anthracite  coal  gave  11.11 
pounds.  All  of  these  figures  are  higher  than  the  correspond- 
ing results  obtained  on  Boiler  No.  43.  From  the  results  of 
a  subsequent  test  on  Boiler  No.  43,  which  was  made  when  it 
was  working  to  a  greater  capacity,  it  appears  that  the  economy 
of  the  boiler  was  effected  by  the  low  rate  of  combustion  under 
which  it  was  worked.  On  the  test  referred  to,  which  was 
made  with  a  mixture  of  pea  and  dust  coal  and  Nova  Scotia 
culm,  having  the  same  proportions  as  those  used  on  Test  No. 
85,  the  rate  of  combustion  was  increased  to  15.5  pounds  of 
coal  per  square  foot  of  grate  per  hour.  The  evaporation  from 
and  at  212  degrees  per  pound  of  coal  was  9.18  pounds,  and 
per  pound  of  combustible  10.77  pounds,  and  these  quantities 
are  about  7  per  cent,  higher  than  those  obtained  on  the  earlier 
tests.  The  temperature  of  the  escaping  gases  on  the  last  test 
was  375  degrees. 

Boiler  No.  44. 

Kind  of  boiler, "Double  deck,"  hor.  ret.  tub. 

Number  used,    .......    Four. 

Horse-power  (collective,  basis  15  square  feet  ),  Three  hundred  and  twenty. 

Tr.    ,     ,.        ,  f  Eureka,    Cumberland,   Bitu- 

Kmdof  coal, j     minous. 

Age, New. 

Boiler  No.  44  consists  of  a  plant  of  four  double-deck  boilers 
set  in  one  battery  of  brick  work  in  the  general  mariner  shown  in 
the  cuts  of  Boilers  No.  41  and  No.  42.  Like  those  referred  to, 
this  boiler  has  two  shells,  one  above  the  other.  The  lower  one 
is  completely  filled  with  tubes,  and  by  this  means  the  area  of 
heating  surface  and  the  area  through  the  tubes  is  much  larger 
in  proportion  to  the  grate  surface  than  is  found  in  ordinary 
tubular  boilers. 


BOILEE  No.  44.  169 

Dimensions  of  Boiler  No.  44. 

Diameter  of  lower  shell,     ..       ..  "  - .       - .        .        .  .  .    54      in. 

Diameter  of  upper  shell,     .       -..-*.•     .        .        »  .  .    32      in. 

Length  of  shells  and  tubes,         .-      .        .         .        V  .  ,  V     12      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,  .  472 

Area  of  water-heating  surface,           ...        .  .  4,972      sq.  ft. 

Area  of  steam-heating  surface,         .....  .  .  320      sq.ft. 

Area  through  tubes,     .        .        •-      ..      •        •        •  .  .  •  19.5  sq.  ft. 

Area  of  grate  surface,         .        .        *'  '    .         .        .  .  .     80      sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,    .        .  .  .   3-8      in. 

Eatio  of  water-heating  surface  to  grate  surfaco,      .  .  .    62.1  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,      .  .    •  .  .      4      to  1 

Ratio  of  grate  to  tube  area,         .        .        .        .        .  .  ,      4.1  to  1 

Results  of  Tests,  Boiler  No.  44.     (Average  of  two.) 

Test  No.  89. 
Manner  of  start  and  stop  and  kind  of  run,      .        .        .        ...       Ordinary. 

Duration,    .         ...         . ......      ,.        .         .        .        .         .  12.25         hrs. 

Coal  consumed,  dry  (  including  wood  equivalent  ),          .      9,000  Ibs. 

Percentage  of  ash,     .        .        .        .        .        .      '.i        .        .     9.7  per  cent. 

Water  evaporated,      .-       .        .        .        .        .        .  .      .    92,355  Ibs. 

Coal  per  hour,    .     ^.        .        ..,.,.        .        .,      741.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .     '   .        .        .9.3  Ibs. 

Water  per  hour,          .        ....        .        ,        .        .        .      7,539.2  Ibs. 

Water  per  hour  per  square  foot  of  water  heating  surf  ace,      .     1.5  Ibs. 

Horse-power  developed,    .        .        .        ...,    <       .        .         231.4        H.  P. 

Boiler  pressure,          .        .        .  ,      .        .  ,     .        .  .      .        .82  Ibs. 

Temperature  of  feed-water,      .        .   .     .        .        .        .          190  deg. 

Temperature  of  escaping  gases,       .        .        .        ....      375  deg. 

Water  per  pound  of  coal,        ^.        .        .        .        .        .        .  10.26         Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .        .  10.86         Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,     .  12.03         Ibs. 

The  economical  result  obtained  on  Boiler  No.  44  exceeds  12 
pounds  of  water  from  and  at  212  degrees  per  pound  of  com- 
bustible. This  is  a  creditable  performance,  though  it  is  no 
higher  than  that  given  by  many  boilers  of  the  ordinary  hori- 
zontal tubular  type,  a  fact  which  shows  that  some  of  the  heat- 
ing surface  in  this  form  of  boiler  fails  to  be  utilized. 

Boiler  No.  45. 

Kind  of  boiler, "  Double  deck"  hor.  ret.  tub. 

Number  used, One. 

Horse-power  (  basis  15  square  feet),      .  One  hundred  and  fifty. 

Kind  of  coal  ("Delaware     and      Lackawanna 

>al'    '  \     anthracite,  broken. 

Age, •  .  •     .        New. 


170  BOILER   TESTS. 

Boiler  No.  45  is  a  double  deck  boiler  similar  in  all  features 
except  size  to  Boilers  No.  41  and  No.  42,  and  the  manner  in 
which  it  is  arranged  and  set  is  shown  in  the  cuts  of  these 
boilers. 

Dimensions  of  Boiler  No.  45. 

Diameter  of  lower  shell,         .        .        .        -.''.".,  66     in. 

Diameter  of  upper  shell,        .        .        .            •"'.       V       .  36     in. 

Length  of  shells  and  tubes,    .         .        .        .        .    J    .        .'r  15     ft. 

Number  of  tubes  3  inches  outside  diameter,          .        .        .  172 

Area  of  water-heating  surface,       .        .        .        .        .        .  2,235     sq.ft. 

Area  of  steam-heating  surface, 70     sq.  ft. 

Area  through  tubes, 7.1  sq.  ft. 

Area  of  grate  surface, 36.6  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,      Air  5-8  in.,  metal  1-2  in. 

Katio  of  water-heating  surface  to  grate  surface,  .        .         .  60.9  to  1 

Katio  of  steam-heating  surface  to  grate  surface,  .        .         .  2  to  1 

Ratio  of  grate  surface  to  tube  area,       .        .        .                 .  5.2  to  1 

Besults  of  Tests,  Boiler  No.  45.     (Average  of  two.  ) 

Test  No.  90. 

Manner  of  start  and  stop  and  kind  of  run,      .        *  ;.,.,.        .         Ordinary. 
Duration,    .        .        .      [*&       .        ;•.-/.  ^  .'v     r»    ,.  -„  .      .11.7  hrs. 

Coal  consumed  ( including  wood  equivalent ),          *        .      6,237  Ibs. 

Percentage  of  ash,     .        .        .        .        .        .        .        .        .8.1  per  cent. 

Water  evaporated, 56,388  '    Ibs. 

Coal  per  hour, 530.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .        .        .         .  14.5  Ibs. 

Water  per  hour, 4,799  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surf  ace,      .    2.1  Ibs. 

Horse-power  developed,     .......         155.1         H.  P. 

Boiler  pressure,          .        .        .        '."'     ,.       .."     Y        .        .79  Ibs. 

Temperature  of  feed  water, 132  deg 

Temperature  of  escaping  gases,        .        .        .        .        .         373  deg- 

Percentage  of  moisture  in  steam, 0.3  per  cent. 

Water  per  pound  of  coal, .  9.04          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          «        .9.76          Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,     .  11.00          Ibs. 

The  tests  on  Boiler  No.  45  were  made  with  damper  wide 
open,  and  therefore  under  conditions  of  maximum  capacity. 
The  chimney  was  of  ample  size,  and  its  height  was  70  feet. 
The  boiler  power  developed  amounted  to  155  horse  power,  or 
a  trifle  more  than  the  nominal  capacity  rated  on  15  square  feet 
of  heating  surface  per  horse  power.  Although  the  boiler 


BOILER  No.   46.  171 

worked  up  to  the  capacity  noted,  it  could  not  properly  be 
called  a  150  horse  power  boiler,  unless  provided  with  a  chim- 
ney of  such  height  that  it  would  produce  that  power  with  con- 
siderably less  than  the  full  draught.  The  low  temperature  of 
the  escaping  gases  shows  that  the  large  area  of  heating  surface 
served  to  absorb  nearly  the  whole  of  the  available  heat  of  the 
products  of  combustion,  and  the  evaporation  per  pound  of 
combustible  from  and  at  212  degrees,  which  was  11  pounds,  is 
a  favorable  result. 

Boiler  No.  46. 

Kind  of  boiler,         .        .        .       -        *     •"  .    Hor.  ret.  tub.  (double-deck) . 
Number  used,   .        ...        .        .        .    Four. 

Horse  power  (collective,  basis  15  square  feet),  Two  hundred  and  ninety. 
Kind  of  coal,    .      _.        .        '.      '•'.        j       .    Cumberland. 

Age,         ".        ._.,...,..,_       .       ...    •  .*        .    Six  years. 

Boiler  No.  46  embraces  a  plant  of  four  double  deck  hori- 
zontal tubular  boilers  set  in  one  battery  of  brick  work.  The 
general  features  of  the  boiler  and  its  setting  are  shown  in  the 
cuts  of  Boilers  No.  41  and  No.  42.  It  is  provided  with  a  flue 
heater,  consisting  of  vertical  cast-iron  pipes,  similar  to  that 
used  with  Boiler  No.  33,  the  location  of  which,  with  reference 
to  boilers  and  chimney,  is  shown  in  ground  plan  in  the  follow- 
ing cut.  This  heater  has  about  one-half  as  much  surface  as 
the  total  heating  surface  of  the  boilers. 


172 


BOILER    TESTS. 


.  J 


-- 

s~ 

V 
\ 
V 

\ 

XVC^C 

^ 

^ 

\, 

S. 

>-- 


1 


BOILER  No.  46,  GROUND  PLAN  SHOWING  LOCATION  OF  BOILERS 
AND  FLUE  HEATER. 


BOILER   No.    46. 


173 


Dimensions  of  Boiler  No.  46. 

Diameter  of  lower  shell,          ..*-.'.-*        •        •        •        •        •      48      in- 

Diameter  of  upper  shell,    .        .        .-,      .        .      '.'•'.        .      30      in. 
Length  of  shells  and  tubes,       .-..,.        .         .         .       14      ft. 

Number  of  tubes  (  collective  )  3  inches  outside  diameter,       .     320 

Area  of  water-heating  surface,         .        .        .       \        .        .4,058      sq.  ft. 

Area  of  steam-heating  surface,         .         .        .         .         .         .     280      sq.  ft. 

Area  of  grate  surface,       .        ...        ...       .        .      70      sq.  ft. 

Area  through  tubes,   .        .        .        .        .        .        .        .        .      13.2  sq.  ft. 

Area  through  flue,      .,..'... 9      sq.  ft. 

Height  of  chimney,  .'       .        ,         ...     .         :         .         .      80     ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          .     Air  5-8  in.,  metal  1  in. 
Ratio  of  water-heating  surface  to  grate  surface,     ...      58     to  1 
Ratio  of  steam-heating  surface  to  grate  surface,     .        *     - •-,        4     to  1 
Ratio  of  grate  surface  to  tube  area,          .        •        •        •        •        5.3  to  1 
Ratio  of  grate  surface  to  flue  area,  .        .        *        .        .        7.8  to  1 

Area  of  heating  surface  in  flue  heater,     ..        .        ,        .         1,920       sq.ft. 


Results  of  Tests,  Boiler  No.  46. 


Test  No.  91.        Test  No.  92. 


Heater  in 

Heater  not 

use. 

in  use. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      .......  hrs. 

12.5 

12,5 

Coal  consumed,    dry   (  including  wood  equiv- 

alent)     Ibs. 

10,659 

10,946 

Percentage  of  ash,      .        .  ^     -  .        .  per  cent. 

7.6 

7 

Water  evaporated,       ...        .        .         .Ibs. 

106,598 

102,261 

Coal  per  hour,      Ibs. 

852.7 

875.6 

Coal  per  hour  per  square  foot  of  grate,        Ibs. 

12.2 

12.5 

Water  per  hour,  ......   Ibs. 

8,527.8 

8,180.8 

Water  per  hour  per  square  foot  of  water-heat- 

ing surface,  .        .        .        .                 .   Ibs. 

2.1 

2 

Horse-power  developed,      .        .        .         H.  P. 

289.9 

277.8 

Boiler  pressure,  ......   Ibs. 

77 

75 

Temperature  of  feed-water  entering  heater,  deg. 

79 

_ 

Temperature  of  feed-water  entering  boiler,deg 
Temperature  of  escaping  gases  leaving  boiler, 

145 

79 

deg. 

361 

342 

Temperature  of  escaping  gases  leaving  heater, 

deg. 

254 

_ 

Draught  suction,          .         .         .         .         .in. 

0.17 

0.22 

Water  per  pound  of  coal,  ....   Ibs. 

10.00 

9.34 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,              Ibs. 

_ 

10.95 

Water  per  pound  of  combustible  from  and  at 

212  degrees,           .         .         .        .        .   Ibs. 

~ 

11.78 

NOTE.  —  The  coal  when  fired  contained  5  per  cent,  of  moisture. 


174 


BOILER    TESTS. 


The  test  on  Boiler  No.  46  had  for  a  principal  object  the 
determination  of  the  economy  of  using  a  flue  heater  with" 
horizontal  tubular  boilers,  which  were  already  provided  with  a 
large  area  of  heating  surface,  the  ratio  of  which  to  grate  sur- 
face was  58  to  1.  The  heater  reduced  the  temperature  of  the 
gases  361°  —  254°  =  107  degrees,  and  increased  the  tempera- 
ture of  the  feed-water  145°  —  79°  =  66  degrees,  and  secured 
thereby  an  increase  in  the  evaporation  per  pound  of  coal 
amounting  to  7  per  cent.  If  the  results  of  Test  No.  91 
are  applied  to  the  plant  as  a  whole,  the  evaporation  per  pound 
of  combustible  from  and  at  212  degrees  becomes  12.68  pounds. 
Looked  at  in  this  way,  the  performance  is  exceedingly  high 
for  this  or  any  other  type  of  boiler,  and  it  shows  what  may  be 
attained  by  employing  an  ample  area  of  heating  surface, 
arranged  in  such  a  manner  as  to  properly  absorb  the  heat. 
Without  the  heater,  the  economy  obtained  is  below  the  best 
performance  of  ordinary  horizontal  tubular  boilers. 


Kind  of  boiler,  .        .        .     !   . 

Number  used, 

Horse-power  (collective,  basis  6  sq.  ft.  ), 
Kind  of  coal, 


Boiler  No.  47. 
|   .        .        .        Plain  cylinder. 
.        .        .        Four. 

Two  hundred  and  twenty. 
Anthracite,  chestnut  No.  2. 


Age, Ten  years. 


BOILER  No.  47,  CROSS  SECTION  THROUGH  FURNACE. 


BOILER  No.   47. 


175 


Boiler  No.  47  em- 
braces four  sets  of 
cylinder  boilers  ar- 
ranged in  the  manner 

~ 

shown  in  the  follow- 
ing cuts.     Each  boiler 
consists   of  three 
shells  placed   over   a 
single     furnace,     the 
lower       portions      of 
which     are     exposed 
their  entire  length  to 
the   heat  of  the  pro- 
ducts of  combustion. 
The    upper    portions 
are  covered  with  brick 
work.      These  boilers 
have   a  ratio  of  only 
7.5     square    feet     of 
heating  surface  to  one 
of    grate.       In    this 
respect  they    possess 
their   special    charac- 
teristic.       The    ratio 
in  a  horizontal  tubu- 
lar boiler,   is  seldom 
below    25   to   1,   and 
the      proportion      of 
water-heating  surface 
in  the  vertical  boiler 
is   seldom   below    15 
to  1. 


176 


BOILER   TESTS. 


Dimensions  of  Boiler  No.  47. 
Diameter  of  shells  (  3  in  each),     .        .        .        . 

Length  of  shells,     .        .        .        ..... 

Area  of  heating  surface,        . 

Area  of  grate  surface,    .        .        .        ."-.'.'•' 

Area  through  flue,  .         .         .        .        .  . 

Height  of  chimney,          .        . 

Width  of  air  spaces  and  metal  bars  in  grates, 

Distance  of  grate  to  shell,      .        . 

Ratio  of  heating  surface  to  grate  surface,     . 

Ratio  of  grate  surface  to  flue  area, 


30     in. 

30     ft. 
1,320     sq.  ft. 
175     sq.  ft. 

10.5  sq.  ft. 
120      ft. 
3-8      in. 

16      in. 
7.5  to  1 

16.7  to  1 


Results  of  Tests,  Boiler  No.  47. 


Test  No.  93. 

Test  No.  94. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinarv. 

Ordinary. 

Duration,      .......  hrs. 

10  .7" 

11.5 

Coal  consumed,  dry   (  including  wood  equiva- 

lent),       Ibs. 

14,061 

12,264 

Percentage  of  ash,      ....  per  cent. 

14 

14.7 

98,256 

83,416 

Coal  per  hour,      Ibs. 

1,308 

1,066.4 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs. 

7.4 

6.1 

Water  per  hour,  ......  Ibs. 

9,140.1 

7,253.6 

Water  per  hour  per   square   foot  of    heating 

surface,         ......   Ibs. 

6.9 

5  5 

Horse-power  developed,     .        .        .         H.  P. 

272 

240 

Boiler  pressure,  Ibs. 

72.7 

71.2 

Temperature  of  feed-water,       .        .        .  deg. 

207 

93 

Temperature  of  escaping  gases,         .        .  deg. 

650 

567 

Water  per  pound  of  coal,  ....   Ibs. 

6.99 

6.80 

Water  per  pound  of  coal  from  and  at  212  de- 

degrees,         ......   Ibs. 

7.27 

7.89 

Water  per  pound  of  combustible  from  and  at 

212  degrees,          Ibs. 

8.44 

9.22 

NOTE.  —  The  coal  when  fired  contained  5  per  cent,  of  moisture.    On  Test  No.  94  the 
ash-pit  doors  were  partly  closed. 

The  tests  on  Boiler  No.  47  exhibit  the  performance  of  plain 
cylinder  boilers  using  one  of  the  small  grades  of  anthracite 
coal  and  working  under  two  different  rates  of  combustion. 
One  noticeable  feature  in  the  results  is  the  high  rate  of  evapo- 
ration which  occurred,  being  6.9  pounds  per  square  foot  of 
heating  surface  per  hour  in  Test  No.  93,  and  5.5  pounds  in 
Test  No.  94.  Another  is  the  high  temperature  of  the  escaping 
gases,  which  was  650  degrees  in  the  first  test,  and  567  degrees 
in  the  second  test.  Both  of  these  are  due  to  the  rela- 
tively small  amount  of  the  heating  surface.  In  view  of  the 


BOILEE  No.   48.  177 

low  results  which  are  often  obtained  on  more  modern  boilers, 
the  performance  here  shown,  must,  under  the  circumstances, 
be  considered  remarkable.  Looking  at  Test  No.  94,  the 
rate  of  evaporation  exceeds  anything  ordinarily  obtained  from 
boilers  of  approved  type,  and  the  temperature  of  the  escaping 
gases  is  correspondingly  high,  but  the  evaporative  result,  viz., 
9.22  pounds  of  water  from  and  at  212  degrees  per  pound  of 
combustible,  is  not  more  than  20  per  cent,  below  the  highest 
that  can  ordinarily  be  obtained  from  the  horizontal  tubular, 
boiler  with  the  class  of  fuel  used. 

Boiler  No.  48. 

Kind  of  boiler, Plain  cylinder. 

Number  used,      ......  One. 

Horse-power   (  basis  6  sq.  f t.  ) ,          .        .  Seventy-seven. 

Age, Several  years. 

Boiler  No.  48  is  of  the  plain  cylinder  type,  arranged  and 
set  in  the  general  manner  shown  in  the  cut  of  Boiler  No.  47. 
Here  four  shells  instead  of  three  are  used,  and  the  setting  of 
the  boiler  is  independent  of  other  boilers.  The  proportion  of 
heating  surface  to  grate  surface  is  somewhat  larger  than  in 
Boiler  No.  47,  being  10.9  to  1,  though  very  far  below  that  of 
good  practice  in  approved  boiler  work. 

Dimensions  of  Boiler  No.  48. 

Number  of  shells, 4 

Diameter  of  each  shell, 30      in. 

Length  of  each  shell, 30.5  ft. 

Area  of  heating  surface, 464      sq.  ft. 

Area  of  grate  surface,     .         . 42.7  sq.  ft. 

Area  through  flue,     .        .' 6      sq.  ft. 

Height  of  chimney, 75      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          Air  5-16  in.,  metal  3-8  in. 

Ratio  of  heating  surface  to  grate  surface,      ....  10.9  to  1 

Ratio  of  grate  surface  to  flue  area, 7.1  to  1 


178 


BOILER    TESTS. 
Results  of  Tests,  Boiler  No.  48. 


Test  No.  95. 

Test  No.  96. 

Kind  of  coal,        .       .  .    *'  „. 

Coke. 

Anthracite 

Pea. 

Manner  of    start  and  stop, 

Thin  fire. 

Thin  lire. 

Kind  of  run, 

. 

Factor  v. 

Factory. 

Duration,      .                           . 

.  hrs. 

10.fi 

11.5 

Coal  consumed,  dry 

.   Ibs. 

5,774 

4,770 

Percentage  of  asli, 

.  per  cent. 

7.7 

13.2 

Water  evaporated, 

.   Ibs. 

30,140 

27,258 

.Coal  per  hour, 

.   Ibs. 

540.9 

414.8 

Coal  per  hour  per  square  foot  of  £ 

crate,    .   Ibs. 

12.8 

9.7 

Water  per  hour,  .... 

.   Ibs. 

2,870.5 

2,370.3 

Water  per  hour    per  square    foot 

of   heating 

surface,          .... 

.   Ibs'. 

6.2 

5.1 

Horse-power  developed, 

H.  P. 

99.7 

82.4 

Boiler  pressure,   .... 

.   Ibs. 

82 

79 

Temperature  of  feed-water, 

.  deg. 

39 

38 

Temperature  of  escaping  gases, 

.  deg. 

Above  GOO 

Above  600 

Water  per  pound  of  coal,    . 

.   Ibs. 

5.22 

5.71 

Water    per    pound  of    coal  from 

and  at  212 

degrees,         .... 

.   Ibs. 

6.37 

6.96 

Water  per  pound  of  combustible 

from  and  at 

212  degrees,  .... 

.   Ibs. 

0.87 

7.97 

The  tests  on  Boiler  No.  48  were  made  to  determine  the  rela- 
tive economy  of  anthracite  pea  coal  and  gas  house  coke,  and, 
incidentally,  the  general  economy  of  the  boiler.  The  evapora- 
tion of  water  per  pound  of  coke  is  8  per  cent,  less  than  the 
evaporation  per  pound  of  coal,  and  this  relation  is  also  that  of 
the  cost  of  fuel  in  the  two  cases,  the  price  per  pound  being  the 
same.  The  effect  of  the  deficiency  of  heating  surface  in  this 
boiler  is  seen  in  the  exceedingly  high  temperature  of  the  gases, 
and  the  consequent  low  degree  of  economy.  Comparing  the 
result  of  Test  No.  96  made  on  this  boiler  with  pea  coal,  with 
Test  No.  36  made  on  horizontal  tubular  boiler  No.  15  with 
similar  fuel,  it  appears  that  the  evaporation  per  pound  of  com- 
bustible is  20.1  per  cent,  less  than  that  obtained  in  the  case  of 
the  improved  form  of  boiler.  Comparing  also  Test  No.  95 
made  on  this  boiler  when  using  coke,  with  No.  67  made  on 
tubular  boiler  No.  31  with  the  same  kind  of  fuel,  it  appears 
that  the  cylinder  boiler  gave  an  evaporation  of  32  per  cent, 
less  water  per  pound  of  combustible,  than  that  obtained  with 
the  tubular  boiler. 


BOILER  No.  49. 


179 


Boiler  No.  49. 

Kind  of  boiler, Plain  cylinder. 

Number  used, One. 

Horse-power  (basis  10  square  feet),  .        .        Thirty-nine. 
Age, Several  years. 

Boiler  No.  49  is  a  plain  cylinder  boiler,  the  general  features 
of  which  are  shown  in  the  cuts  of  Boiler  No.  47.  The  pecu- 
liarity of  this  type  of  boiler  is  the  small  proportion  of  heating 
surface  to  grate  surface,  which  here  was  10.9  to  1. 

Dimensions  of  Boiler  No.  49. 
Diameter  of  shells,  three  in  number,         .        .         .         .  30     in. 

Length   of  shells, 30     ft. 

Area  of  heating  surface, 394     sq.  ft. 

Area  of  grate  surface, 36.1  sq.  ft. 


Area  through  flue,      .........         5.4  sq. 

Height  of  chimney, 120     ft. 


ft. 


"Width  of  air  spaces  and  metal  bars  in  grates, 

Distance  of  grate  to  shell, 

Distance  of  flat  bridge  to  shell,        .... 
Ratio  of  heating  surface  to  grate  surface, 
Katio  of  grate  surface  to  flue  area, 

Eesults  of  Tests,  Boiler  No.  49. 


1-2 

17 

4 

10.1 


in. 
in. 
in. 
to  1. 


6.6  to  1. 


Test  No.  97. 

Test  No.  98. 

Test  No.  99. 

Kind  of  coal,                                j 

Bituminous 
Cumberland. 

Bituminous 
Cumberland. 

Anthracite 
Chestnut  No.  2. 

Condition  of  fire  at  start  and  ( 

Thin  fire. 

Banked  fire. 

Ordinary  with 

stop,                                        \ 

preliminary 
heating. 

Kind  of  run,          .        .        . 

Ordinary. 

Ordinarv. 

Continuous. 

Duration,      .         ...        .  hrs. 

9.5 

12.2 

5.2 

Coal    consumed,  dry   (  including 

wood  equivalent  ),         .   Ibs. 

2,579 

3,338 

2,014 

Percentage  of  ash,       .  per  cent. 

10 

10.3 

19.3 

Water  evaporated,         .        .Ibs. 

17,270 

22,119 

9,643 

Coal  per  hour,       .        .        .Ibs. 

271.4 

272.5 

383.6 

Coal  per  hour  per  square  foot  of 

grate,      .        .        .         .  Ibs. 

7.5 

7.5 

10.6 

Water  per  hour,    .        .        .   Ibs. 

1,817.9 

1,805.6 

1,836.6 

Water  per  hour  per  square  foot 

of  heating  surface,        .  Ibs. 

4.6 

4.6 

4.7 

Horse-power  developed,        H.  P. 

60.8 

60.8 

62 

Boiler  pressure      .        .        .Ibs. 

80 

80 

83 

Temperature  of  feed-water,  cleg. 

78 

90 

90 

Temperature  of   escaping  gases, 

deg. 

Melts  zinc 

_ 

_ 

Draught  suction,            .        .in. 

0.18 

0.17 

0.16 

Water  per  pound  of  coal,     .  Ibs. 

6.70 

6.63 

4.94 

Water  per  pound  of  coal  from 

and  at  212  degrees,        .   Ibs. 

7.86 

7.70 

5.75 

Wat^r  per  pound  of  combustible 

from  and  at  212  degrees,  Ibs. 

8.74 

8.59 

7.03 

180 


BOILEE    TESTS. 


The  tests  on  Boiler  No.  49  had  for  an  object  the  determina- 
tion of  the  general  economy  of  this  form  of  boiler,  the  rela- 
tive economy  of  Cumberland  coal  and  anthracite  chestnut  No. 
2  coal,  and  the  loss  occasioned  by  banking  fires.  The  results 
all  show  a  very  low  degree  of  economy.  That  obtained  on 
Test  No.  97  is  more  than  25  per  cent,  inferior  to  the  best 
results  obtained  on  boilers  of  approved  type.  Attention  needs 
only  to  be  directed  to  the  deficient  heating  surface,  and  the 
consequent  large  amount  of  waste  heat  in  the  gases,  which  in 
this  case  were  hot  enough  to  melt  zinc,  to  account  for  the 
result.  Comparing  Test  No.  99  with  Test  No.  97,  the  evap- 
oration per  pound  of  chestnut  No.  2  coal  is  26  per  cent,  less 
than  that  of  Cumberland  coal.  The  loss  produced  by  banking 
a  Cumberland  coal  fire,  as  indicated  by  Tests  No.  97  and  No. 
98,  appears  to  be  2  per  cent. 


Boiler  No.  5O. 


Kind  of  boiler,  .        .  /      .        . 

Number  used,     .        .        .'/-...        -    ..> 

Horse-power  (  collective,  makers'  rating). 

Kind  of  coal,     .        .•'.'.. 
Age,    .        .        .       ,.-.   -.•;-•      •  • 


Galloway. 

Six. 


* 


George's  Creek  Cumberland. 
Three  months. 

Boiler  No.  50  consists 
of  a  plant  of  six  Gallo- 
way boilers,  having  the 
general  features  shown  in 
the  following  cuts.  This 
is  an  internally  fired  boiler 
having  two  furnaces  in 
each  shell.  The  heat- 
ing surface  consists  largely 
of  vertical  water  tubes  of 

conical  shape,  which  ex- 
BOILER  No.  50,  CROSS  SECTION  THROUGH 

FURNACES.  tend  from  top  to  bottom 

of  the  large  flue  which  passes  from  the  combustion  chamber  at 
the  end  of  the  furnaces  to  the  end  of  the  boiler.  The  products 
of  combustion,  on  leaving  the  furnaces,  pass  forward  through 
this  flue,  thence  backward  beneath  the  shell,  finally  entering 


BOILER  No.  50. 


181 


the  chimney  flue  from  the  front  end.  In  this  boiler  the  ratio 
of  heating  surface  to  grate  surface  is  much  smaller  than  is 
generally  found  in  horizontal  tubular  boilers  of  approved  type. 


182  BOILER   TESTS. 

Dimensions  of  Boiler  No.  50. 

Diameter  of  each  shell, 84     in. 

Length  of  shell, 28     ft. 

Area  of  heating  surface, 5,628      sq.  ft. 

Area  of  grate  surface,        .         . 217.6  sq.  ft. 

Area  through  flue,       .         .         .         .* 60      sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,        Air  1  in.,  metal  3-8  in. 
Height  of  chimney,   .         .         ...        .         .         .         .     230      ft. 

Ratio  of  heating  surface  to  grate  surface,        .        .        .        .       25.9  to  1 

Ratio  of  grate  surface  to  flue  area,  .         ...        .        .         3.6  to  1 

Eesults  of  Test,  Boiler  No.  50. 

Test  No.  100. 
Manner  of  start  and  stop,         ..        ...        .  Running  with  thin  tire. 

Kind  of  run,       .        .        .        .        ...      .        .        .  ..  '    .        .     Continuous. 

Duration,    .        .        .      t  .        »        .        .        .;       .V     .        .12.7  hrs. 

Coal  consumed,  dry, 47,638  Ibs. 

Percentage  of  ash,     .        .  .        f        .        .        .  6.0  percent. 

Water  evaporated,     .        .        .,...'.        .        .370,448  Ibs. 

Coal  per  hour,     .         ..„.;.         .         .         .      3,756.9  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .        .        .        ..  17.3  Ibs. 

Water  per  hour,          .        .        .        .        .        .        .        .    29,210.3  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,        .  5.2  Ibs. 

Horse-power  developed,    .  J,    .        .        .        .        .        .      1,024.3         H.  P. 

Boiler  pressure,  .         .         .         /       .         .         .        .  51.2  Ibs. 

Temperature  of  feed-water,     .        .        .        .        .        .  36.7  deg. 

Temperature  of  escaping  gases,        .        .        .        .        .         533  deg. 

Draught  suction,        .        .         . 0.64  in. 

Percentage  of  moisture  in  steam, 7     per  cent. 

Water  per  pound  of  coal,          .        .        .    ;    .        .      '  .  7.78          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .  9.40          Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,    .10.00          Ibs. 

Th6  test  on  Boiler  No.  50  shows  the  performance  of  an 
internally  fired  boiler  of  special  type,  worked  at  a  high  rate  of 
capacity.  The  rate  of  combustion  was  17.3  pounds  of  coal 
per  square  foot  of  grate  per  hour,  and  this  was  obtained  by 
the  employment  of  a  draught  which  reached  the  excessive 
pressure  of  0.64  inches.  Owing  to  the  small  amount  of  heat- 
ing surface,  the  rate  of  evaporation  was  exceedingly  high, 
being  5.2  pounds  per  square  foot  of  heating  surface  per  hour. 
This  rate,  however,  was  insufficient  to  work  the  boilers  to 
their  normal  capacity,  as  based  on  the  builders'  rating  of  the 
power.  The  temperature  of  the  escaping  gases  is  above  the 
standard  of  good  economy,  though  not  so  high  as  might  be 


BOILER   No.   50.  183 

expected  in  view  of  the  conditions  under  which  the  boiler  was 
operated.  The  evaporation  per  pound  of  combustible  from  and 
at  212  degrees,  which  is  10  pounds,  is  much  below  good  boiler 
work,  especially  when  considering  the  quality  of  the  steam. 
The  calorimeter  showed  that  the  steam  contained  7  per  cent,  of 
moisture.  On  this  test  no  deduction  was  made  for  the  coke, 
ashes  or  soot  which  was  deposited  behind  the  bridge  walls. 
Judging  from  the  results  of  observations  on  ,a  single  boiler, 
such  an  allowance  would  increase  the  evaporative  result  about 
4  per  cent.  The  number  of  firemen  employed  for  the  six 
boilers  was  three,  and  they  were  not  specially  skilled  in  firing. 
The  capabilities  of  this  type  of  boiler  are  best  shown  by  a 
subsequent  test,  made  on  a  single  boiler  of  the  plant,  which 
was  in  the  hands  of  an  expert  fireman.  On  this  test  the  same 
class  of  fuel  was  used  as  before,  and  the  coal,  ashes  and  soot, 
deposited  in  the  flue  behind  the  bridge  wall,  were  allowed  for. 
The  main  results  were  as  follows  : 

Coal  per  square  foot  of  grate  per  lionr,    .        .        .        .        .  21.3  Ibs. 

Percentage  of  ash,     .         . .7.0  per  cent. 

Water  per  square  foot  of  heating  surface  per  hour,        .        .    7.6  Ibs. 

Boiler  pressure, 07.7  Ibs. 

Temperature  of  feed-water,      .        .        .        .        .        .         107.0  cleg. 

Temperature  of  escaping  gases,        .        .  .        .         575.0  cleg. 

Draught  suction, 0.57          in. 

Percentage  of  moisture  in  steam,     .....  0.5  per  cent. 

Water  evaporated  from  and  at  212  deg.  perlb.  of  combustible,  11.06          Ibs. 

In  view  of  the  high  temperature  of  the  gases  shown  in  this 
test,  an  evaporation  of  11.06  pounds  must  be  considered  as 
excellent  work.  If  the  heating  surface  under  these  conditions 
had  been  increased  so  as  to  absorb  the  waste  heat,  as,  for 
example,  by  means  of  a  suitable  flue  heater,  the  evaporative 
result  would  readily  have  been  brought  up  to  the  highest 
standard  of  economy. 

•   Boiler  No.  51 . 
Kind  of  boiler,     ........     Vertical  tub.ular  (  rolling  pin  ) . 

Number  used,       .        ...        .        .     One. 

Horse-power  (basis  10  sq.  ft.  ),          .        .     One  hundred  and  forty. 

Kind  of  rofll  /  Delaware     and     Lackawanna, 

•\     Anthracite,  Broken. 
Age, Ten  years. 


BOILER    TESTS. 


BOILER  No.    51,  VERTICAL    ELEVATION. 


Boiler  No.  51  is  a  verti- 
cal tubular  boiler  of  the 
so-called  "  Rolling  Pin  " 
form,  the  principal  features 
of  which  are  shown  in  the 
following  cut.  In  this 
boiler  the  main  shell  is 
completely  filled  with  tubes, 
with  the  exception  of  the 
central  space  extending  be- 
tween the  water  leg  and 
the  dome.  The  grate  sur- 
face forms  an  annular  ring 
surrounding  the  water  leg. 
The  brick  setting  consists 
of  a  plain  brick  wall,  sur- 
rounding the  shell,  and 
extending  up  to  a  height  of 
about  10  feet  above  the 
upper  tube  sheet.  This  is 
surmounted  by  a  wrought 
iron  smoke  stack.  The 
water  line  is  ordinarily  car- 
ried to  a  point  about  3  feet 
below  the  top  of  the  main 
shell,  and  above  this  point 
the  tubes  are  uncovered. 
A  considerable  portion  of 
the  heating  surface  is  thus 


made  steam  heating  surface,  and  the  boiler  produces  steam 
which  is  in  a  more  or  less  superheated  condition.  This  form 
of  vertical  boiler  has  a  proportion  of  30  square  feet  of  total 
heating  surface  to  one  of  grate,  and  about  two  thirds  of  this  is 
water-heating  surface. 


BOILER   No.  51. 


185 


Dimensions  of   Boiler  No.  51. 

Diameter  of  main  shell,          .-...>.•        .       > ..  . 
Diameter  of  drum  and  water  leg,  .    .  .  .>        .        . 

Length  of  main  shell  and  tubes,     .         .        .         - 
Number  of  tubes  2  inches  outside  diameter,        •  .    • 
Area  of  water-heating  surface,      .    ,".:•'..' 
Area  of  steam-heating  surface,      .         ... 

Area  of  total  heating  surface,       ..    .  -. 
Area  of  grate  surface,    .        ..... 

Area  through  tubes,         .        .        . 
Width  of  air  spaces  and  metal  bars  in  grates, 
Area  through  stack,         .        •-.     -      .'•', 
Height  of  stack,      .        ."      .        .        /       .        . 
Katio  of  water-heating  surface  to  grate  surface, 
Ratio  of  steam-heating  surface  to  grate  surface, 
Ratio  of  total  heating  surface  to  grate  surface,    . 
Ratio  of  grate  to  tube  area,    .        .        .        . 


90  in. 

29  in. 

9ft. 

248 

426 
1,367 
45.6 
4.1 
1-2 
8.7 
60 
20.6 
9.3 
30 
11 


9  in. 

sq.  ft 

sq.  ft 
sq.  ft. 
sq.  ft. 

sq. 
in. 

sq. 
ft. 
to  1 
to  1 
to  1 
to  1 


ft 


ft. 


Results  of  Tests.     Boiler  No.    51. 


TestNo.ioi. 

Test  Xo.l02. 

Test  No.103. 

Position  of  damper, 

Wide 
open. 

Partially 
closed. 

Partially 
closed. 

Manner  of  start  and  stop  and  kind  of 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,           .....  hrs. 

11.7 

11.2 

11.7 

Coal  consumed  (including  woodequiva-. 

lent),          Ibs. 

9,161 

5,705 

5,897 

Percentage  of  ash,  .   •;    ...        .  percent. 

8.5 

8.6 

8.4 

Water  evaporated,            .•  .     .        .  Ibs. 

61,355 

44,597 

48,735 

Coal  per  hour,        x  .        .        .        .   Ibs. 

783 

507.1 

504 

Coal  per  hour  per  square  foot-  of  grate, 

Ibs. 

17.1 

11.1 

11 

Water  per  hour,        .        .        .         .Ibs. 

5,244 

3,964.2 

4,165.4 

Water  per  hour  per  square  foot  of  water- 

heating  surface,         .        .  *      .  Ibs. 

5.6 

4.3 

3.6 

Horse-power  developed,  .  •     »    ;     .H.P. 

169.8 

128.2 

134.8 

Boiler  pressure,        .        .        .        .  Ibs. 

78 

79 

80 

Temperature  of  feed-water,    .        .  deg. 

132 

132 

134 

Temperature  of  escaping  gases,      .  deg. 

600 

480 

434 

Number  of  degrees  of  superheating,  deg. 

- 

90 

14 

Water  per  pound  of  coal,          .        .  Ibs. 

6.70 

7.82 

8.26 

Water  per  pound  of  coal  from  and  at  212 

degrees,     Ibs. 

7.23 

8.75 

9.22 

Water  per  pound  of  combustible  from 

and  at  212  degrees,    .         .         .Ibs. 

8.18 

9.56 

10.07 

186  BOILER    TESTS. 

The  tests  on  Boiler  No.  51  show  the  performance  of  this 
type  of  boiler  under  various  conditions,  when  burning  anthra- 
cite broken  coal.  Test  No.  102  was  made  under  the  ordinary 
working  conditions.  Test  No.  101  was  made  with  damper 
wide  open,  so  as  to  work  the  boiler  to  its  maximum  capacity. 
Test  No.  103  was  made  under  similar  conditions  to  that  of  No. 
102,  with  the  single  exception  that  the  water  line  was  carried 
to  a  higher  point.  The  amount  of  water  heating  surface  on 
this  test  was  1159  square  feet,  and  that  of  steam  heating 
surface  208  square  feet,  the  ratios  of  these  surfaces  to  the 
grate  surface  being  respectively  25.4  and  4.6  to  1. 

The  evaporative  results  given  in  the  Table  take  no  account 
of  the  superheated  condition  of  the  steam.  The  amount  of 
superheating  in  the  case  of  Test  No.  102  was  90  degrees. 
What  allowance  should  be  made  for  the  superheat  depends 
upon  the  character  of  the  work  which  the  steam  is  called  upon 
to  perform.  The  increased  value  of  superheated  steam  is 
never  less  than  the  equivalent  of  the  excess  of  the  heat  which 
it  contains  over  saturated  steam,  whatever  the  use  to  which  it 
is  applied.  For  operating  engines  it  has  been  found  that  the 
value  of  superheat  is  at  least  double  that  of  heat  expended  in 
evaporation.  If  an  allowance  for  superheating  is  made  on 
Test  No.  102  according  to  the  heat  added,  the  equivalent 
evaporative  result  per  pound  of  combustible  from  and  at  212 
degrees  is  increased  from  9.56  to  9.94  pounds.  This  result 
is  not  so1  high  as  that  obtained  from  horizontal  tubular  boilers, 
working  under  favorable  conditions.  The  temperature  of  the 
escaping  gases  on  this  test,  which  is  480  degrees,  is  excessive 
for  anthracite  coal,  and  it  is  evident  that  the  inferior  result  is 
due,  in  a  measure,  at  least,  to  the  waste  heat  at  this  point. 

The  effect  of  increasing;  the  water  heating  surface  and  re- 

o  o 

ducing  the  amount  of  superheating  is  seen  in  the  results  of 
Test  No.  103.  The  amount  of  superheating  is  only  14  degrees, 
and  the  temperature  of  the  escaping  gases  is  reduced  to  434 
degrees.  The  evaporative  result  is  higher  than  that  given  on 
the  low  water  test,  being.  10. 07  from  and  at  212  degrees  per 
pound  of  combustible,  the  increase  amounting  to  about  5  per 


BOILER  No.  51.  187 

cent.  Allowing  for  superheating  as  before  according  to  the 
quantity  of  heat  added,  the  results  of  the  two  tests  are  respec- 
tively 9.94  pounds  and  10.15  pounds,  and  the  difference 
between  them  is  about  2  per  cent.  The  increase  in  the  water 
heating  surface  enabled  the  boiler  to  utilize  a  larger  propor- 
tion of  the  heat  of  combustion  of  the  coal  to  the  extent  of 
about  2  per  cent. 

A  comparison  of  Tests  No.  101  and  No.  102  shows  the 
unfavorable  effect  produced  upon  the  vertical  type  of  boiler  by 
a  high  rate  of  combustion.  The  quantity  of  coal  burned  in  a 
given  time  in  Test  No.  101  was  54  per  cent,  larger  than  in 
Test  No.  102,  and  the  evaporation  per  pound  of  coal  was 
reduced  14.4  per  cent.  This  reduction  is  accounted  for  by 
the  increased  temperature  of  the  escaping  gases,  which  was 
from  480  degrees  to  600  degrees.  The  amount  of  power 
developed  on  the  capacity  test  was  large,  and  the  ease  here 
shown  with  which  the  vertical  boiler  generates  steam  should 
not  be  lost  sight  of.  With  a  stack  only  60  feet  high,  the 
boilers  developed  21  per  cent,  more  than  the  rated  capacity 
(  without  allowance  for  the  greater  efficiency  of  superheated 
steam  ),  and  the  rate  of  combustion  was  17.1  pounds  of  coal 
per  square  foot  of  grate  per  hour. 

Boiler  No.  52. 

Kind  of  boiler,         .        /       •  •        •        Vertical  tubular  with  fire-box. 

Number  used,  .        .        .        .  .     .  ,        One. 

Horse-power  (  basis  10  sq.  ft.  ),  .        .        Twenty. 

Kind  of  coal,    .        .     :   . •  .  ..-  .        .  ,  Anthracite,  Lehigh,  egg. 

Age,           .        .        .         .  .-•  •  .'.',••*        Four  months. 

Boiler  No.  52  is  of  the  vertical  type,  arranged  in  the  manner 
shown  in  the  following  cut.  It  is  supported  by  a  brick  ash  pit, 
but  otherwise  it  has  no  brick  setting,  the  exterior  surface  being 
covered  with  a  non-conducting  cement.  The  steam,  before 
leaving  the  boiler,  passes  through  a  chamber  in  the  interior  of 
the  shell.  The  top  and  bottom  of  this  chamber  are  connected 
by  means  of  tubes  which  surround  the  respective  fire  tubes 
of  the  boiler,  the  annular  space  between  the  two  tubes 


188 


BOILER    TESTS. 


Illllllllllllll 


52 


being  filled  with  water.  When 
the  boiler  is  in  operation,  there  is 
a  circulation  of  water  from  the 
bottom  of  the  boiler  upward 
through  these  annular  spaces,  to 
the  top  of  the  boiler,  and  thence 
downward  through  an  outer  row 
of  tubes,  which  are  provided  for 
the  return  of  the  water.  The 
upper  ends  of  the  fire  tubes  are 
bare,  and  the  steam,  on  leaving 
the  steam  space,  is  by  this  means 
superheated.  Owing  to  the  sub- 
sequent passage  of  the  steam 
through  the  drum,  the  superheat 
is  absorbed,  and  the  steam  leaves 
the  boiler  in  a  saturated  state. 
The  boiler  is  surmounted  by  a 
smoke  stack,  which  is  so  placed 
that  it  interfered  with  the  clean- 
ing of  the  tubes,  and  these  had 
not  been  brushed  out  since  the 
boiler  was  started. 


BOILER  No.  52,  VERTICAL  ELE- 
VATION AND  SECTION. 

Dimensions  of  Boiler  No.  52. 

Diameter  of  shell,      .,»»    . 
Diameter  of  fire-box  and  grate,        ... 
Height  between  heads  and  length  of  tubes,     . 
Number  of  tubes  2  inches  outside  diameter,    . 

Height  of  fire-box, 

Area  of  heating  surface  (total),     .... 
Area  of  grate  surface, 


40     in. 
33     in. 
9  ft.  6  in. 
42 

24     in. 
205      sq.  ft. 
6.1  sq.  ft. 


BOILER  No.  52. 


189 


Area  through  tubes,   .         .        .        ..       .   _    '.        .       >•'••«,,-  0.7  sq.  ft. 

Area  through  stack,  .        .         .         .......         .  0.78sq.  ft. 

Height  of  stack,         .        .        ...        .:.:.'•      -Y  52      ft. 

Ratio  of  total  heating  surface  to  grate  surface,       .         *      ;  .  =  33.5  to  1 

Ratio  of  grate  surface  to  tube  area,        . v        .    .   •••«..'     ..  ,,     ,  8.7  to  1 

Results  of  Tests,  Boiler  No.  52. 


rest  JNO.  iu4. 

±esi  iso.  luo. 

( 

Ordinary 

Ordinary 

Manner  of  start  and  stop,  .         .         .     •    ..^v-f 

withprelimi- 

with  prelimi- 

1 

naryheating. 

nary  heating. 

Kind  of  run,         .        .  r     .       -.  .      . 

Continuous. 

Continuous. 

Duration,      .'        .  hrs. 

7.25 

7.25 

Coal  consumed  (including  wood  equivalent),  Ibs. 

664 

404 

Percentage  of  ash,      ....  per  cent. 

8.9 

9.4 

Water  evaporated,       .    '    ..      .  ;'.  '-...-      .   Ibs. 

5,676 

3,597 

Coal  per  hour,      Ibs. 

91.6 

55.8 

Coal  per  hour  per  square  foot  of  grate,     .   Ibs. 

15 

9.1 

Water  per  hour,  ......   Ibs. 

782.9 

496.2 

Water  per  hour  per  square  foot  of  total  heating 

surface,         .         .        .                 .        .   Ibs. 

3.8 

2.42 

Horse-power  developed,      .        .        ;         H.  P. 

24.5 

15..  5 

Boiler  pressure,  .         .         .         ...'.    .         .   Ibs. 

89 

91 

Temperature  of  feed-water,       -„••«•        •  deg. 

163 

182 

Temperature  of  escaping  gases,         .        .  deg. 

596 

446 

Water  per  pound  of  coal,  ....   Ibs. 

8.55 

8.90 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,       Ibs. 

9.30 

9.52 

Water  per  pound  of  combustible  from  and  at 

212  degrees,  .         .         ..    /••...   -..,,,-     .   Ibs. 

10.22 

10.51 

The  tests  on  Boiler  No.  52  were  made  with  two  rates  of 
combustion,  viz.,  15  pounds  and  9.1  pounds  per  square  foot  of 
grate  per  hour.  The  high  rate  of  combustion  in  Test  No.  104 
is  noticeable,  considering  the  low  height  of  the  stack,  which 
was  52  feet,  and  this  was  not  the  maximum,  as  the  damper  was 
partially  closed.  The  arrangement  of  tubes  in  the  vertical 
type  of  boiler,  with  stack  directly  above,  is  favorable  for  the 
production  of  a  large  capacity  with  a  feeble  draught,  and  this 
fact  is  here  exemplified.  The  results  of  these  tests  furnish 
evidence  that  the  use  of  a  fire  box  in  vertical  boilers  is  advan- 
tageous. Comparing  Test  No.  105  on  this  boiler,  with  Test 
No.  102  made  on  vertical  boiler  No.  51  which  is  set  in  brick 
work,  there  is  a  noticeable  improvement  in  favor  of  the  fire- 
box boiler,  the  two  quantities  being  respectively  10.51  pounds 


190  BOILER   TESTS. 

and  9.94  pounds,  allowance  here  being  made  for  the  superheat. 
Notwithstanding  the  small  size  of  the  fire-box  boiler,  and  the 
foul  condition  of  the  tubes,  it  secured  much  the  better  result. 
A  comparison  of  the  two  tests  on  this  boiler  shows  unmis- 
takably that  under  equally  favorable  conditions,  a  rapid  com- 
bustion is  more  economical  than  a  slow  combustion.  The 
evaporation  on  test  No.  104  with  rapid  combustion  is  less 
than  3  per  cent,  below  that  on  the  other  test,  while  the  temper- 
ature of  the  gases  is  150  degrees  higher.  If  the  waste  heat  of 
the  gases  had  been  utilized  by  the  employment  of  a  heater,  or 
by  otherwise  increasing  the  heating  surface,  the  performance 
would  have  been  improved  ( judging  from  the  results  of 
heater  tests  elsewhere  given)  at  least  10  per  cent.,  thus 
leaving  7  per  cent,  or  more  net  improvement  due  to  more 
rapid  combustion. 

Boiler  No.  53. 

Kind  of  boiler,        .        .        .  .        .,.      v        .  .  Vertical  tubular. 

Number  used,           .    '    .        .  .       v       ..      .  .  One. 

Horse-power  (basis  10  sq.  ft.  ),  .  y     .  •      '.        .  .  Seventy-five. 

Age,          «       ' .    ;:  V        .  '•'•;•*    -  .1    '..-'_.''->'"  ..  New. 

Boiler  No.  53  is  a  vertical  tubular  boiler  of  the  same  general 
form  as  that  shown  in  the  cut  of  Boiler  No.  52.  Instead  of 
being  provided,  however,  with  a  fire  box,  as  in  the  one 
referred  to,  it  has  a  brick  furnace,  and  furthermore  the  steam 
is  discharged  from  the  boiler  immediately  after  its  generation, 
without  passing  through  the  interior  chamber.  The  exterior 
surface  of  the  shell  is  protected  with  a  somewhat  inefficient 
covering  of  cement.  The  boiler  is  provided  with  a  forced 
draught,  which  is  produced  by  a  blower  discharging  under  the 
ash  pit.  For  the  purpose  of  burning  screenings  on  test  No. 
108  a  plate  was  employed  in  place  of  .the  ordinary  grate,  and 
this  was  perforated  with  one  half  inch  holes,  located  1J  inches 
from  center  to  center.  The  tubes  of  the  boiler  were  not 
cleaned  during  the  test,  and  had  not  been  cleaned  since  the 
boiler  was  started  two  weeks  before. 


BOILER  No.   53. 


191 


Dimensions  of  Boiler  No.  oo. 

Diameter  of  shell,      .         .         .        .     -   .'       .        .  .  64  in. 

Height  of  shell  and  length  of  tubes,        .        ...  14  ft. 

Number  of  tubes,  2  1-2  inches  outside  diameter,     .  .  88 

Diameter  of  brick  furnace,       •.        •* ,     '".        ..        .  .  54  in. 

Area  of  water-heating  surface,          .        .        .        .  .  513  sq.  ft. 

Area  of  steam-heating  surface,          ,       _.        .      ...  '  •  248  sq.ft. 

Area  of  grate  surface,        .        .        .        .        .        .  .  15.9  sq.  ft. 

Area  through  tubes,    .         .        ...         .         .  .         .       2.4  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  .      Air,  5-8  in.,  metal,  3-4  in. 

Area  through  stack,    .         ..       .       *.        .        .        .  .  5.9  sq.ft. 

Height  of  stack,          .         .         .         .,       .         .         .  .  60  ft. 

Distance  from  grate  to  tube  sheet,     .       V       .        .  .  4  ft. 

Ratio  of  water-heating  surface  to  grate  surface,      .  .    •         32.3  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,       .  .  15.6  to  1 

Ratio  of  grate  to  tube  area,        .   .     .        ...       .,       .  .  6.5  to  1 

Eesults  of  Tests,  Boiler  No.  53. 


Test  No.  106. 

Test  No.  107. 

Test  No.  108. 

c 

Anthracite 

Anthracite 

Anthracite 

Kind  of  coal,                                  ^ 

Schuylkill, 

Schuylkill, 

Schuylkill, 

1 

Broken. 

Broken. 

Screenings. 

Draught,        ..... 

Natural. 

Forced. 

Forced. 

r 

Ordinary 

Ordinary 

Ordinary 

Manner  of  start  and  stop,    . 

with  prelim- 
inary heat- 

with prelim- 
inary heat- 

with prelim- 
inary heat- 

I 

ing. 

ing. 

ing. 

Kind  of  run, 

Continuous. 

Continuous. 

Continuous. 

Duration,       ....  hrs. 

10 

10.7 

7.7 

Coal   consumed,   dry   (including 

wood   equivalent),        .    Ibs. 

2,452 

4,134 

3,010 

Percentage  of  ash,         .  per  cent. 

11.6 

13.6 

13.4 

Water  evaporated,        .        .Ibs. 

19,583 

29,846 

19,937 

Coal  per  hour,       .         .        .Ibs. 

245.2 

384.5 

392.4 

Coal  per  hour  per  square  foot  of 

grate,      ....   Ibs. 

15.4 

24.1 

24.7 

Water  per  hour,    .        '.        .  Ibs. 

1,958.3 

2,776.4 

2,599.4 

Water  per  hour  per    square   foot 

of  water-heating  surface,  Ibs. 

3.8 

5.4 

5.1 

Horse-power  developed.        H.  P. 

64.3 

91.2 

85.4 

Boiler  pressure,     .         .        .   Ibs. 

61 

73.2 

73.1 

Temperature  of  feed-water,  deg. 

125 

125 

124 

Temperature  of  escaping  gases, 

deg. 

478 

573 

505 

Number  of    degrees     of    super- 

heating,          .         .        .  deg. 

42 

59 

51 

Water  per  pound  of  coal,    .   Ibs. 

7.98 

7.21 

6.62 

Water  per  pound  of  coal  from 

and  at    212  degrees,      .   Ibs. 

8.95 

8.10 

7.45 

Water  per  pound  of  combustible 

from  and  at  212  degrees,  Ibs. 

10.13 

9.38 

8.61 

192  BOILER    TESTS. 

The  tests  on  Boiler  No.  53  were  made  to  determine  the 
economy  of  the  boiler  when  burning  anthracite  coal,  both  with 
natural  and  forced  draught,  and  that  obtained  when  using  athra- 
cite  screenings  with  forced  draught.  Comparing  test  No.  107 
with  No.  106,  the  use  of  the  blower  increased  the  power 
developed  by  the  boiler  from  64.3  horse  power  to -9 1.2  horse 
power,  or  42  per  cent.,  and  this  was  accompanied  by  a  reduc- 
tion in  the  evaporation  per  pound  of  combustible  of  7.5  per 
cent.  After  allowing  for  the  small  difference  in  the  amount  of 
superheating,  the  reduction  becomes  6.7  per  cent.  The  effect 
of  the  higher  rate  of  combustion  was  to  increase  the  tempera- 
ture of  the  escaping  gases  from  478  to  573  degrees,  and  to 
this  large  increase  in  the  amount  of  waste  heat  may  be 
attributed  the  reduction  in  economy  noted.  Comparing  these 
results  with  those  obtained  from  boilers  having  a  less  propor- 
tion of  water  heating  surface,  it  is  seen  that  this  boiler  has  the 
advantage.  In  Boiler  No.  51  for  example,  the  ratio  of  water 
heating  surface  to  grate  surface  is  20.6  to  1,  and  the  evapora- 
tion per  pound  of  combustible  from  and  at  212  degrees, 
corrected  for  superheating,  is  9.94  pounds.  In  Boiler  No.  53, 
under  consideration,  the  ratio  of  water  heating  surface  to 
grate  surface  is  32.3  to  1,  and  the  result  obtained,  corrected 
for  superheating,  is  10.34  pounds  of  water  per  pound  of  com- 
bustible. The  result  obtained  by  the  use  of  screenings  with 
forced  draught  compares  favorably  with  that  obtained  under 
the  same  circumstances  with  the  standard  coal,  being  inferior 
to  the  coal  result  only  8.1  per  cent.  No  allowance  is  made  in 
the  tests  with  forced  draught  for  the  cost  of  power  required  to 
operate  the  blower. 


Boiler  No  54. 

Kind  of  boiler,           .        .        .        .        .  Vertical  tubular  (rolling  pin ). 
Number  used,     .               • '.        .        .        .  One. 
Horse-power  (  basis  10  square  feet  ),        .  One  hundred  and  forty. 
...    ,    f        ,  ( Two  parts  Anthracite  Screen- 
Kind  of  coal,      ...        ....  |     mgs,  one  part  Cumberland. 

Age,    .        .        .     '  .  .'••••..      .        .        .  Ten  years. 


BOILEE  No.   54. 


193 


Boiler  No.  54  is  a 
vertical  tubular  boiler 
arranged  and  set  in 
the  manner  shown  in 
the  following  cut.  The 
style  of  setting  differs 
from  the  ordinary  prac- 
tice, the  sides  of  the 
furnace  being  provided 
with  perforated  tiles, 
through  which  air  is 
admitted  above  the  fuel. 
The  air  is  first  passed  up 
and  down  through  ducts 
in  the  walls,  before  it 
is  discharged  into  the 
furnace. 


BOILER   No.  .54,  VERTICAL  ELEVATION. 


Dimensions  of  Boiler  No.  54. 

Diameter  of  main  shell, 

Diameter  of  drum  and  water  leg,     .... 
Length  of  main  shell  and  tubes,        .        .        . 
Number  of  tubes,  2  inches  outside  diameter, 


Area  of  steam-heating  surface, 

Area  of  total  heating  surface,  ... 

Area  of  grate  surface, 

Area  through  tubes,  .        . 

Area  through  flue,      .        .        .        .        .        . 

Height  of  chimney,  .         .         .         .         .        . 

Width  of  air  spaces  and  metal  bars  in  grates, 


90      in. 

29      in. 

.         9  ft.  9  in. 
.      248 

936  sq.  ft. 
.  517  sq.  ft. 
.  1,453  sq.  ft. 

45.6  sq.  ft. 
.      •   4.1  sq.  ft. 
2.8  sq.  ft. 
.      125      ft. 

1-2    in. 


194 


BOILER   TESTS. 


Ratio  of  water-heating  surface  to  grate  surface, 
Ratio  of  steam-heating  surface  to  grate  surface, 
Ratio  of  total  heating  surface  to  grate  surface, 
Ratio  of  grate  to  tube  area,      ; 
Ratio  of  crate  to  flue  area, 


Eesults  of  Tests,  Boiler  No.  54. 


21.1  to  1 

10.7  to  1 

31.8  to  1 
11      to  1 
16.1  to  1 


Test  No.  109. 

Test  No.  110. 

Test  No.  111.  1  Test  No.  112. 

f 

Mixture  2  parts  Anthracite 

George's 

Anthracite 

Kind  of  coal,    .        .      4 

Screenings,  l  part  Cumber- 

Creek   Cum- 

Lehigh. 

1 

land. 

berland 

Broken. 

Conditions  as  to  admis- 

Air 

Air 

Air 

Air 

sion  of  air  over  fuel, 

admitted. 

excluded. 

excluded. 

excluded. 

Manner  of  start  and  stop 

and  kind  of  run, 

Ordinary. 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,          .        .  hrs. 

11 

11.7 

11.7 

12.5 

Coal  consumed,  dry  (  in- 

cluding wood  equiva- 

lent),        .         .   Ibs. 

5,399 

6,211 

4,070.4 

5,592 

Percentage    of    ash, 

per  cent. 

18.8 

16.7 

8.2 

15.1 

Water  evaporated,      Ibs. 

33,210 

40,001 

31,888 

37,504 

Coal  per  hour,          .  Ibs. 

483.2 

528.6 

346.5 

447.4 

Coal  per  hour  per  square 

foot  of  grate,    .  Ibs. 

10.7 

11.6 

7.3 

9.8 

Water  per  hour,       .  Ibs. 

3,019.1 

3,404.3 

2,713.8 

3,000.3 

Water  per  hour  per  square 

foot  of  water-heating 

surface,     .        .  Ibs. 

3.2 

3.6 

2.9 

3.2 

Horse-power    developed, 

H.  P. 

104.G 

118.1 

94 

103.8 

Boiler  pressure,       .   Ibs. 

72.5 

72.5 

72.7 

72.2 

Temperature     of     feed- 

water,        .        .  deg. 

42 

42 

44 

44 

Temperature  of  escaping 

gases,         .        .  deg. 

443 

434 

413 

449 

Number  of    degrees    of 

superheating,    .  deg. 

93 

93 

73 

89 

Draught  suction,      .     in. 

0.26 

0.32 

0.07 

0.05 

Number  of  firings,  . 

22 

31 

23 

15 

Number  of  times  slice  bar 

or  stoker  used, 

14 

22 

22 

3 

Water  per  pound  of  coal, 

Ibs. 

6.15 

6.44 

7.83 

6.71 

Water  per  pound  of  coal 

from  and  at  212   de- 

grees,        .        .  Ibs. 

7.46 

7.79 

9.46   ' 

8.11 

Water  per  pound  of  com- 

bustible from  and  at 

212  degrees,       .   Ibs. 

9.06 

9  27 

10.27 

9.54 

NOTE.  — The  coal  when  fired  contained  10  per  cent,  of  moisture. 

The    first    two    tests    on    Boiler   No.    54,    viz.,  tests  No. 
109  and  No.   110,   had    for  an    object    the    determination  of 


BOILER  No.   54. 


195 


the  effect  which  the  admission  of  air  above  the  fuel  has 
upon  the  economy  and  capacity  of  the  boiler.  The 
damper  was  kept  in  a  constant  position  for  both  tests, 
and  there  was  a  steady  draught  of  0.7  inch  on  the  chimney 
side  of  the  damper.  The  effective  draught  in  the  boiler  flue 
was  0.26  inch  when  the  air  was  admitted  and  0.32  inch  when 
it  was  excluded,  and,  as  a  consequence,  the  power  developed 
was  increased, by  excluding  the  air,from  209.2  horse  power  to 
236.2  horse  power,  an  increase  of  13  per  cent.  In  the  matter 
of  economy,  the  exclusion  of  air  was  followed  by  an  increase 
of  4.3  per  cent,  in  the  evaporation  per  pound  of  coal,  and  of 
2.3  per  cent,  per  pound  of  combustible. 

Test  No.  110  taken  in  connection  with  tests  No.  Ill  and  No. 
112,  form  a  series  of  tests  which  show  the  relative  economy 
of  different  kinds  of  fuel.  On  each  of  these  three  tests  the 
air  ducts  remained  closed.  The  evaporation  per  pound  of 
Cumberland  coal  was  16.6  per  cent,  greater,  and  that  per 
pound  of  mixed  fuel  4  per  cent,  less,  than  the  performance 
with  anthracite  coal.  The  cost  of  fuel  required  to  evaporate 
30,000  pounds  of  water  from  and  at  212  degrees,  at  the  prices 
which  ruled  at  the  time  of  the  tests,  is  as  follows  : 


Cumberland. 

Anthracite 
Broken. 

Mixture. 

Cost  per  ton  of  2,200  pounds,     . 
Cost  for  30,000  pounds  of  steam, 

.      $5  50 
7  81 

$5  50 
9  24 

$3  50 
6  03 

From  this  it  appears  that  the  cost  of  Cumberland  coal 
required  to  do  a  given  amount  of  work  was  15.5  per  cent, 
less,  and  that  of  the  mixture  34.7  per  cent,  less,  than  the  cost 
of  anthracite  coal. 

The  relatively  small  amount  of  draught  required  in  burning 
the  standard  grades  of  coal  is  noticeable,  although  the  boiler 
developed  somewhat  less  than  the  rated  power,  and  the  rate  of 
combustion  was  low.  The  draught  on  test  No.  112  is  less 
than  one-sixth  of  the  full  capacity  of  a  good  chimney.  The 
Cumberland  coal  required  a  slightly  stronger  draught  than  the 


196  BOILEE   TESTS. 

anthracite  coal,  and  the  mixed  fuel  required  six  times  as  much. 

The  relative  labor  of  firing  the  various  coals  is  seen  in  the 
number  of  times  of  firing  and  using  the  slicing  bar.  The 
mixed  fuel  is  at  the  greatest  disadvantage  in  this  respect. 

The  economical  results,  as  a  whole,  must  take  into  account 
the  character  of  the  steam,  which  in  the  various  cases  was 
superheated  from  73  degrees  to  93  degrees.  Making  the 
most  favorable  allowance  for  the  increased  value  of  the  steam 
in  this  condition,  the  results  are  much  below  that  obtained 
from  the  best  types  of  boilers.  The  small  proportion  of  water 
heating  surface,  the  consequent  rapid  evaporation  per  square 
foot  of  that  surface,  and  the  resulting  high  temperature  of  the 
escaping  gases,  are  characteristic  of  this  type  of  boiler,  and 
account  for  the  unfavorable  character  of  the  results. 

Boiler  No.  55. 

Kind  of  boiler, Vertical  tubular. 

Number  used, Five. 

Horse-power  (collective,  basis  10  sq.  ft.  ),       Four  hundred  and  seventy-five. 
Age,        .        .        .        .  .        .        .     One  year. 

Dimensions  of  Boiler  No.  55. 

Diameter  of  shell, 64     in. 

Length  between  heads  and  length  of  tubes,     .        .        .        .       14     ft. 
Number  of  tubes  (  collective  ) ,  3  inches  outside  diameter,      .      420 

Area  of  water-heating  surface, 3,300     sq.  ft. 

Area  of  steam-heating  surface, 1,455     sq.  ft. 

Area  of  total  heating  surface, 4,755     sq.  ft. 

Area  of  grate  surface, 157.5  sq.  ft. 

Area  through  tubes, 17.2  sq.  ft. 

Area  through  flue, 27.1  sq.  ft. 

Distance  of  grate  to  tube  sheet, 3  ft.  7  in. 

Ratio  of  water-heating  surface  to  grate  surface,  .  .  .  29.0  to  1 
Ratio  of  steam-heating  surface  to  grate  surface,  .  .  . "  9.2  to  1 
Ratio  of  grate  to  tube  area,  .  .  .  .  .  •  ;  9.1  to  1 


BOILER  No.   55. 
Results  of  Tests,  Boiler  No.  55. 


197 


Test  No.  113. 

Test  No.  114. 

Test  No.  115. 

Test  No.  116. 

Number  of  boilers,  . 

Five. 

Five. 

One. 

One. 

Kind  of  coal,    . 

Anthracite 
Lehigh 
Broken. 

Anthracite 
Lehigh 
Broken. 

Anthracite 
Lehigli 
Broken. 

Mixture  3 
parts  screen- 
ings.   1   part 
Cumberland 

I 

coal. 

Manner  of  start  and  stop 

and  kind  of  run, 

Ordinary. 

Ordinary. 

Ordinary. 

Ordinary. 

Duration,          .        .  hrs. 

11.5 

11.5 

12 

12.5 

Coal  consumed  (including 

wood  equiv  a  1  e  n  t  )  , 

Ibs. 

25,904 

22,925 

3,527 

3,614 

Percentage    of    ash, 

per  cent. 

10.3 

13.2 

13.2 

16.5 

Water  evaporated,       Ibs. 

158,705 

148,686 

22,599 

22,017 

Coal  per  hour,          .   Ibs. 

2,252 

1,990 

293.9 

289.1 

Coal  per  hour  per  square 

foot  of  grate,    .   Ibs. 

14.3 

12.7 

9.3 

9.2 

"Water  per  hour,        .  Ibs. 

13,800.4 

12,929.2 

1,883.2 

1,761.4 

Water  per  hour  per  square 

foot  of  water-heating 

surface,      .        .Ibs. 

4.2 

3.9 

2.8 

2.8 

Horse-power    developed, 

H.  P. 

555.6 

522.5 

65.4 

61.4 

Boiler  pressure,        .   Ibs. 

72.1 

72 

72.1 

70.2 

Temperature     of      feed- 

water,         .        .  deg. 

126 

121 

39 

39 

Temperature  of  escaping 

gases,         .         .  deg. 

545 

509 

417 

462 

Number   of    degrees    of 

superheating,    .  deg. 

80 

73 

71 

70 

Draught  suction,      .     in. 

0.16 

0.16 

0.09 

0.03 

Water  per  pound  of  coal, 

Ibs. 

6.13 

6.49 

6.41 

6.09 

Water  per  pound  of  coal 

from    and    at    212 

degrees,     .        .Ibs. 

6.87 

7.33 

7.77 

7.38 

Water  per  pound  of  com- 

bustible from  and  at 

212  degrees,       .  Ibs. 

7.63 

8.43 

8.96 

8.85 

198 


BOILER    TESTS. 


Boiler  No.  55  consists  of  a 
plant  of  five  vertical  tubular 
boilers  of  the  type  shown  in 
the  following  cut.  This  boiler 
consists  of  a  plain  vertical 
shell,  containing  tubes  placed 
in  two  sections,  arranged  with 
an  open  space  between  them 
for  purposes  of  inspection  and 
cleaning.  It  is  set  with  a 
brick  furnace,  the  walls  of 
which  extend  about  half  way 
up  on  the  sides  of  the  boiler. 
Above  this  point  the  shell  is 
covered  with  non-conducting 
cement.  The  boilers  are  fitted 
with  tubes  having  an  external 
diameter  of  3  inches,  which  is 
somewhat  larger  than  those 
ordinarily  used  for  vertical 
boilers. 

Tests  No.  113  and  No. 
114  were  made  on  the  full 
plant  of  five  boilers,  while 
tests  No.  115  and  No.  116 

were  made  on  a  single  boiler  of  the  plant.  The  first 
three  tests  show  the  performance  of  the  boilers  with  anthra- 
cite coal,  working  under  three  different  rates  of  combus- 
tion, the  highest  being  14.3  pounds  per  square  foot  of  grate 
per  hour,  and  the  lowest  9.3  pounds.  There  is  a  continuous 
improvement  in  the  evaporative  result  as  the  rate  is  decreased, 
though  the  best  result  obtained  cannot  be  looked  upon  as 
favorable.  The  highest  performance  is  8.96  pounds  of  water 
from  and  at  212  degrees  per  pound  of  combustible,  with  71 
degrees  of  superheating.  The  low  degree  of  economy  which 
was  realized  may  be  attributed  in  part  to  the  high  temperature 
of  the  escaping  gases,  and  in  part  to  loss  produced  by  radia- 


m 
_  E 

SSB  
===*  _ 

r^* 

( 

•  '47/ 

55 

BOILER  No.  55,  VERTICAL 
ELEVATION. 


BOILER  No.   56.  199 

tion  from  the  brick  furnace,  and  by  leakage  of  air  through  the 
brick  work.  The  large  area  through  the  tubes  doubtless  con- 
tributed in  some  degree  to  the  unfavorable  result. 

The  low  draught  required  for  a  vertical  boiler  is  here  notice- 
able, 16  inches  being  sufficient  to  burn  14.3  pounds  of  anthra- 
cite coal  per  square  foot  of  grate  per  hour.  In  the  case  of  the 
test  with  the  mixed  fuel  the  draught  suction  was  .03  inch. 

Comparing  the  results  of  test  No.  116,  made  with  mixed  fuel, 
with  that  of  No.  115,  made  with  anthracite  coal,  the  evapora- 
tion with  the  mixture,  based  on  coal,  is  5  per  cent,  less,  and 
based  on  combustible,  1  per  cent,  less,  than  that  with  the 
standard  fuel.  Taking  into  account  the  cost  of  these  fuels  at 
the  time  of  the  tests,  the  economy  in  favor  of  the  mixed  fuel 
amounts  to  33  per  cent. 

Boiler  No.  56. 
Kind  of  boiler,        ......  Vertical  tubular  (  nest ) . 

Number  used, Two. 

Horse-power  (  collective,  basis  10  sq.  ft.  ),  Three  hundred  and  eighty. 
Kind  of  coal,  •  •'  •  •  •  •  Anthracite  chestnut  No.  2. 
Age,  *  ..,.•*  .  .  .  Ten  years. 

Dimensions  of  Boiler  No.  56. 

Diameter  of  central  shell, .       36  in. 

Length  of  central  shell,    . 21  ft. 

Diameter  of  outer  shells   (  6  in  numbor,  each),      .         .         .       30  in. 

Length  of  outer  shells  and  length  of  tubes,  .  .  .  .  10  ft. 
Number  of  tubes  (collective),  2  inches  outside  diameter,  .  516 

Area  of  water-heating  surface, 2,224  sq.  ft. 

Area  of  steam-heating  surface, 1,566  sq.  ft. 

Area  of  total  heating  surface, 3,790  sq.  ft. 

Area  of  grate  surface,       .-„•'.• 143  sq.  ft. 

Area  through  tubes,  ...<...        .        ,        .         .         8.6  sq.  ft. 

Area  through  flue,      ••--...        .    -\  .     • 10  sq.  ft. 

Ratio  of  water-heating  surface  to  grate  surface,    .  •  •    .        .-       15.5  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,    .        .        .       11  to  1 

Ratio  of  grate  surface  to  tube  area,         .        .        .        .        .       16.6  to  1 


200 


VOILEli    TESTS. 


I 


ffl 


ffl 


ffl 


Boiler  No.  56  is  a  ver- 
tical tubular  boiler,  con- 
sisting of  six  vertical 
shells  filled  with  tubes, 
surrounding  and  com- 
municating with  a  central 
shell,  as  shown  in  the 
following  cut. 

The  whole  is  enclosed 
in  a  circular  wall  which 
forms  the  setting.  The 
flue  space  is  separated 
from  the  furnace  space  by 
iron  plates  fitting  around 
the  shells.  This  type  of 
boiler  does  not  differ  in 
principle  from  the  ordi- 
nary vertical  boiler,  but 
it  differs  somewhat  in  the 
proportions.  It  has  a 
low  proportion  of  water- 

— —  heating  surface  to  grate 

BOILER  No.  56,  VERTICAL  ELEVATION.  gurfilcej  namely,  15.5  to 

1,    and  a  correspondingly  high  proportion   of  steam-heating 
surface.     The  tube  area  is  small. 

Results  of  Test,  Boiler  No.  56. 

Manner  of  start  and  stop  and  kind  of  run, 
Duration,    ......... 

Coal  consumed,  .        . 

Percentage  of  ash, 

Water  evaporated, 

Coal  per  hour, 

Coal  per  hour  per  square  foot  of  grate,    . 

Water  per  hour, 

Water  per  hour  per  square  foot  of  water-heating  surface, 
Horse-power  developed,     .        .        .        .        .        •        •       242.8 
Boiler-pressure.,          .        .        .        •        • 

Temperature  of  feed-water, 120 

Temperature  of  escaping  gases, 468 

Number  of  degrees  of  superheating 31 


Test  No.  117. 

. 

Ordinary. 

11 

hrs. 

11,862 

Ibs. 

12.9 

per  cent. 

82,584 

Ibs. 

1,078.4 

Ibs. 

.  7.5 

Ibs. 

7,507.6 

Ibs. 

j,        3.4 

Ibs. 

242.8 

H.  P. 

83 

Ibs. 

120 

deg. 

deg. 


BOILER  No.   56.  201 

Draught  suction, 0.08  in. 

Water  per  pound  of  coal,        *.        .        .        .    •    .        .  6.96  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .  7.86  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,        8.91  Ibs. 

The  test  on  Boiler  No.  56  shows  the  performance  of  a  verti- 
cal boiler,  which  was  deficient  in  heating  surface,  when  using 
one  of  the  small  grades  of  anthracite  coal.  The  rate  of  com- 
bustion is  low,  and  there  is  consequently  a  small  amount  of 
power  developed.  The  power  is  nearly  40  per  cent,  below 
the  nominal  capacity.  In  spite  of  this  low  rate  the  tempera- 
ture of  the  escaping  gases  is  high,  being  468  degrees,  and  the 
economic  result  is  inferior,  not  only  to  the  best  class  of 
boilers,  but  also  to  the  best  performance  of  this  particular 
class.  In  this  boiler,  as  in  other  vertical  boilers  set  in  brick 
work,  there  is  a  large  exterior  surface  exposed  to  the  air. 
This  surface  not  only  causes  radiation,  but  owing  to  the  un- 
stable condition  of  brick- work  which  has  had  a  long  period  of 
service,  it  provides  many  avenues  for  the  entrance  of  air  both 
to  the  furnace  and  to  the  flue  space.  The  effect  of  unneces- 
sary admission  of  air  is  to  reduce  the  efficiency  of  the  fuel  and 
to  lower  the  temperature  of  the  gases.  The  last-named  effect 
causes  the  apparent  indication  of  waste  heat  to  be  much  less 
than  the  real  quantity. 

Boiler  No.  57. 
Kind  of  boiler,  .        .        .        ...        .        Vertical  tubular  (  rolling  pin  ). 

Number  used,     .        .        ....        .        One. 

Horse-power  (  basis  10  square  feet  ),       .        One  hundred  and  forty. 
Kind  of  coal,     .        .        .        .  .        Anthracite  Lackawanna,  egg. 

Age, Several  years. 

Boiler  No.  57  is  a  vertical  boiler  of  the  rolling  pin  type, 
having  the  general  features  shown  in  the  cut  of  Boiler  No.  51. 
Dimensions  of  Boiler  No.  57. 

Diameter  of  main  shell, 90  in. 

Diameter  of  drum  and  water  leg,      ......       31  in. 

Length  of  main  shell  and  tubes, 10  ft. 

Number  of  tubes,  2  inches  outside  diameter,  ....     248 

Area  of  water-heating  surface, 897  sq.  ft. 

Area  of  steam-heating  surface, 505  sq.  ft. 

Area  of  total  heating  surface, 1,402  sq.  ft. 


202 


BOILEE    TESTS. 


Area  of  grate  surface, 45      sq.  ft. 

Area  through  tubes,    .     .    .     .....     .    .        »       -.         .  4.1  sq.ft. 

Height  of  chimney,   .        .     "v    . 90      ft. 

Width  of  air  spaces  and  metal  bars  in  grates,          .  Air  5-8  in.,  metal  1-2  in. 

Distance  of  grate  to  tube  sheet,       .         .        .        •.„  "    •.        .  2  ft.  8  in. 

Ratio  of  water-heating  surface  to  grate  surface,     .        .        .  19.9  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,     .        .        .  11.3  to  1 

Ratio  of  grate  surface  to  tube  area,          .        .        .        .        .  10.9  to  1 

Results  of  Tests,  Boiler  No.  57. 


Test  No.  us. 


Test  No.  119. 


Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,     hrs- 

10.37 

10.12 

Coal  consumed   (  including  wood  equiva- 

lent) ,    Ibs. 

5,602 

6,472 

Percentage  of  ash,     .        .        .  per  cent. 

17 

17.1 

Water  evaporated,      ....   Ibs. 

35,482 

39,646 

Coal  per  hour      Ibs. 

540.4 

637.7 

Coal  per  hour  per  square  foot  of  grate, 

Ibs. 

12 

14.2 

Water  per  hour,  .....  Ibs. 

3,422.7 

3,915.7 

Water  per  hour  per  square  foot  of  water- 

heating  surface,    ....   Ibs. 

3.8 

4.4 

Horse  power  developed,      .        .        H.  P. 

119.8 

137 

Boiler  pressure,  .        .        •        •        .Ibs. 

79.5 

77.8 

Temperature  of  feed-water,       .        .  deg. 

52 

49 

Temperature  of  escaping  gases,        .  deg. 

520 

- 

Draught  suction,         ....     in. 

0.12 

0.24 

Number  of  degrees  of  super-heating,  deg. 

65 

89 

Water  per  pound  of  coal,  .        .        .  Ibs. 

6.33 

6.13 

Water  per  pound  of  coal  from  and  at  212 

degrees,         Ibs. 

7.61 

7.37 

Water  per  pound  of  combustible  from  and 

at  212  degrees,      ....   Ibs. 

9.17 

8.87 

The  tests  on  Boiler  No.  57  show  the  performance  of  a  verti- 
cal tubular  boiler  under  two  rates  of  combustion,  both  of 
which  are  comparatively  high  for  the  small  proportion  of  heat- 
ing surface  to  grate  surface  which  is  here  found,  viz.,  19.9  to 
1.  As  in  all  boilers  of  this  class,  the  temperature  of  the 
escaping  gases  is  high,  and  there  is  a  correspondingly  low 
economic  result,  There  is  a  small  reduction  in  the  evapora- 
tion produced  by  the  high  rate  of  combustion.  It  is  notice- 
able in  the  comparison  of  the  two  tests  that  it  required  double 
the  draught  suction  to  increase  the  rate  of  combustion  from  12 
pounds  to  14.2  nounds  per  square  foot  of  grate  per  hour. 


BOILEE   No.   58. 
Boiler  No.  58. 

Kind  of  boiler .     .        .        .        .        .        .  Vertical  tabular. 

Number  used, Two. 

Horse-power  (  collective,  basis  12  sq.  ft.  ),  Two  hundred  and  ten. 

Kind  of  coal,        .        .        .        .         .        .  Clearfleld  bituminous. 

Age,      .        •        «        •        *        •         •        •  Four  years. 

Boiler  No.  58  is  a  vertical 
boiler  of  somewhat  novel  form, 
the  general  features  of  which 
are  shown  in  elevation  in  the 
following  cut.  The  boiler  is  of 
the  fire  box  type,  the  water  leg 
of  which  is  provided  with  two 
opposite  openings  for  the  intro- 
duction of  fuel.  The  tubes  are 
divided  into  three  sections  ar- 
ranged in  concentric  circles. 

O 

The  first  section  embraces  the 
inner  tubes.  These  carry  the 
products  of  combustion  upward 
from  the  furnace  to  a  combus- 
tion chamber,  which  is  located 
inside  the  boiler,  below  the 
water  line.  The  second  em- 
braces those  in  the  next  circle, 
and  through  these  the  products 
of  combustion  pass  downward. 
The  third  section  embraces  the 
outer  tubes,  which  carry  the 
gases  upward  to  the  space  sur- 
rounding the  steam  dome, 


203 


BOILER  No.  58,  VERTICAL 
SECTION. 


whence  they  finally  enter  the  chimney  flue.  The  proportion 
of  water  heating  surface  to  grate  surface,  which  is  35.1  to  1, 
is  nearly  double  that  which  is  found  in  the  rolling  pin  type  of 
boiler,  and  the  proportion  of  steam  'heating  surface  to  grate 
surface  is  less  than  one-half  of  that  found  in  the  boiler  noted. 
The  arrangement  of  tubes,  which  provides  for  a  downward 
current  of  the  gases  through  a  part  of  their  passage,  secures  a 


204  BOILER   TESTS. 

distribution  of  the  heating  surface  whereby  it  is  made  efficient 
throughout  its  whole  extent. 

Dimensions  of  Boiler  No.  58. 

Diameter  of  shell  1\  feet  high,          .        .  ,     .  ||  .        .        .  8      ft. 

Diameter  of  fire-box, 6.5  ft. 

Number  of  tubes  in  first  section  (  collective  ) ,  3  inches  out- 
side diameter, "  .  ...  280 

Number  of  tubes  in  second  section  (  collective  ) ,  4  inches 

outside  diameter,  .  .  .  .  .  ...  76 

Number  of  tubes  in  third  section  (  collective  ),  4£  inches  out- 
side diameter,  .........  76 

Length  of  tubes  in  first  and  second  sections,           .        .        .  5      ft. 

Length  of  tubes  in  third  section,      ......  7.5  ft. 

Diameter  of  dome,     .........  6      ft. 

Height  of  dome, 7.5  ft. 

Area  of  water-heating  surface, 2,273      sq.  ft. 

Area  of  steam-heating  surface,         ......  263      sq.  ft. 

Area  of  total  heating  surface, 2,536     sq.  ft. 

Area  of  grate  surface, 64.8  sq.  ft. 

Area  through  flue, 12      sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,            Air  1-2  in.,  metal  3-8  in. 

Ratio  of  water-heating  surface  to  grate  surface,     .        .        .  35.1  to  1 

Ratio  of  steam-heating  surface  to  grate  surface,     .        .        .  4     to  1 

Ratio  of  grate  surface  to  smallest  tube  area,  .        .        .        .  12.1  to  1 

Eesults  of  Test,  Boiler  No.  58. 

Test  No.  120. 

Manner  of  start  and  stop  and  kind  of  run,      ....  Ordinary. 

Duration,    ..........         11.5  hrs. 

Coal  consumed,  dry  (  including  wood  equivalent ),          .    7,682  Ibs. 

Percentage  of  ash, 9.3  per  cent. 

Water  evaporated,      .        .        .        .        .        .        .        .72,207  Ibs. 

Coal  per  hour, 668  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .         10.3  Ibs. 

Water  per  hour, 6,278.9  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,     .  2.8  Ibs. 

Horse-power  developed, .,..     v.  213.2  H.  P. 

Boiler  pressure, .        .         76.5  Ibs. 

Temperature  of  feed-water,      .        . .       •        •        .        •         66  deg. 

Temperature  of  escaping  gases,        .        .        .        .        .       423  deg. 

Water  per  pound  of  coal,          .        .        .        .    ;    » J  «.           9.4  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,      11.19  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .         12.29  Ibs. 

The  test  on  Boiler  No.  58  exhibits  the  performance  of  a 
vertical  tubular  boiler,  so  planned  as  to  overcome  the  losses 
that  attend  the  work  of  vertical  boilers  as  ordinarily  set  in 


BOILER  No.   59.  205 

brick  work.  Unnecessary  air  leakage  into  the  furnace  is  pre- 
vented by  the  use  of  a  tire  box.  The  ratio  of  heating  surface 
to  grate  surface  is  as  large  as  that  found  in  many  efficient 
horizontal  tubular  boilers.  The  rate  of  combustion  is 
moderately  high,  and  the  temperature  of  the  escaping  gases  is 
not  excessive  for  bituminous  coal.  All  these  conditions  are 
favorable  to  economy,  and  they  go  hand-in-hand  with  the  high 
character  of  the  evaporative  result  which  the  test  gives.  An 
evaporation  of  12.29  pounds  of  water  from  and  at  212  per 
pound  of  combustible,  which  was  obtained  in  this  case,  is 
seldom  exceeded  by  any  type  of  boiler. 

Boiler  No.  59. 

Kind  of  boiler,          .        .        .        ...        Vertical  tubular  ( rolling  pin  ) . 

Number  used,  .        .      .  .  '      .        .        .        Two. 

Horse-power  (  collective,  basis  10  sq.  ft.  ),      Two  hundred  and  eighty. 
Kind  of  coal,    .        .  .        .        .        George's  Creek  Cumberland. 

Age,  .        .        .        .        .        .        .        Twelve  years. 

Boiler  No.  59  embraces  a  plant  of  two  vertical  boilers  of 
the  rolling  pin  type,  of  the  general  form  shown  in  elevation  in 
the  cut  of  Boiler  No.  51.  They  are  provided  with  a  flue 
heater,  the  location  of  which,  with  reference  to  the  boilers,  is 
shown  in  ground  plan  in  the  following  cut.  The  heater  con- 
sists of  vertical  cast-iron  pipes,  similar  to  that  of  Boiler  No. 
33,  the  exposed  surface  of  which  has  nearly  as  large  an  area 
as  that  of  the  total  water  heating  surface  of  the  boilers. 
Dimensions  of  Boiler  No.  59. 

Diameter  of  main  shell,     .        .        .        .        .        .        .        .       90      in. 

Diameter  of  drum  and  water  leg,     .        .        .        .        .        .       30     in. 

Length  of  main  shell  and  tubes, 10      ft. 

Number  of  tubes  (collective  ),  2  inches  outside  diameter,      .     496 

Area  of  water-heating  surface,          ,        ,        .       V       .        .1,880      sq.ft. 

Area  of  steam-heating  surface,       . 924      sq.  ft. 

Area  of  grate  surface,       .        .        ...        .        .        .90      sq.  ft. 

Area  through  tubes, .        ...         8.2  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  Air  1-2  in.,  metal  5-8  in. 

Height  of  chimney, .       80      ft. 

Ratio  of  water-heating  surface  to  grate  surface,  .  .  .  20.9  to  1 
Ratio  of  steam-heating  surface  to  grate  surface,  .  ,  .  10.3  to  1 
Ratio  of  grate  surface  to  tube  area,  >  .  .  .  .  11  to  1 
Area  of  heating  surface  in  flue  heater,  .  *.  .  .  •  .1,600  sq.ft. 


206 


BOILER    TESTS. 


BOILER  No.  59,  GROUND  PLAN  SHOWING  LOCATION  OF  BOILERS 
AND  FLUE  HEATER. 


BOILER  No.  59, 

Eesults  of  Tests,  Boiler  No.  59. 


207 


Test  No.  121. 

Test  No.  122. 

Heater  in 

Heater  not 

use. 

in  use. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,  ......  hrs. 

11.5 

11.5 

Coal    consumed,  dry    (including    wood 

7,856 

10,282 

Percentage  of  ash,    .        .        .  per  cent. 

8 

8.4 

Water  evaporated,     .        .        .        .   Ibs. 

^2,002 

72,959 

Coal  per  hour,    .        .        .        .        .Ibs. 

683.1 

894-.  1 

Coal  per  hour  per  square  foot  of  grate, 

Ibs. 

7.6 

9.9 

6,261 

6,344.3 

Water  per  hour  per  square  foot  of  water- 

heating  surface,          .        .        .    .  P. 

3.3 

3.4 

Horse-power  developed,    .        .  •      Hlbs. 

210.3 

213.6 

Boiler  pressure,          ....   Ibs. 

58 

59 

Temperature    of     feed-water    entering 

heater,         deg. 

88 

— 

Temperature     of     feed-water    entering 

boiler,          .         .         .         .        .  deg 

225 

85 

Temperature  of   escaping  gases  leaving 

boiler,          ....         -deg. 

618 

645 

Temperature  of    escaping  gases  leaving 

heater,         .....  deg. 

365 

_ 

Number  of  degrees  of  superheating,  deg. 

50 

52 

Draught  suction,        ....     in. 

0.09 

_ 

Water  per  pound  of  coal,          .        .Ibs. 

9.16 

7.10 

Water  per  pound  of   coal  from  and  at 

212  degrees,         ....  Ibs. 

_ 

8.23 

Water  per  pound  of  combustible   from 

and  at  212  degrees,     .        .         .   Ibs. 

~ 

8.99 

NOTE.  —The  coal  when  fired  contained  3  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  59  had  for  a  principal  object  the 
determination  of  the  economy  secured  by  the  use  of  a  flue 
heater  in  connection  with  vertical  boilers.  They  are  of  special 
interest  in  view  of  the  large  amount  of  waste  heat  which 
ordinarily  escapes  to  the  flue  in  this  type  of  boiler.  In  test 
No.  121  the  heater  was  in  operation,  while  in  test  No.  122  the 
heater  was  shut  off,  and  the  gases  passed  directly  to  the 
chimney.  The  employment  of  the  heater  reduced  the  temper- 
ature of  the  escaping  gases  618° — 365°=  253  degrees,  and 
increased  the  temperature  of  the  feed  water  225° — 88°  =  137 
degrees,  resulting  in  an  increase  of  the  evaporation  per  pound 
of  coal  of  7.10  to  9.16  pounds  or  29  per  cent.  When  the 
heater  was  not  in  use,  the  economy  secured  was  noticeably 


208  BOILER   TESTS. 

low,  which  could  not  be  otherwise  with  the  high  flue  tempera- 
ture which  existed,  viz.,  645  degrees. 

Considering  the  results  of  test  No.  121  as  applied  to  the 
plant  as  a  whole,  the  evaporation  per  pound  of  combustible 
from  and  at  212  becomes  11.54  pounds.  Allowing  for  the 
superheating,  which  amounted  to  52  degrees,  the  result  is 
equivalent  to  11.84  pounds  of  water  evaporated.  This  is  not 
far  below  the  best  results  commonly  obtained  from  well  pro- 
portioned horizontal  tubular  boilers  not  provided  with  a  flue 
heater. 

Boiler  No.  6O. 
Kind  of  boiler,         .        *        .        .        .    .   .    Vertical  tubular  ( fire  box ) . 

Number  used,    .        .        .        .        .        .        .    Two. 

Horse-power  (  collective,  basis  13  sq.  ft.  ),         Two  hundred  and  sixty. 
Kind  of  coal,    .        .        .        .        .  •      .        .     George's  Creek  Cumberland. 

Age,  .        .        .-       .        .        i        . ....--.        .     Sixteen  months. 

Dimensions  of  Boiler  No.  60. 

Diameter  of  shell,      .        .        .        .        ,        .        .        .  .       60     in. 

Height  between  heads  and  length  of  tubes,     .       ..        •  .       15      ft. 
Number  of  tubes  (  collective  ),  2-£  inches  outside  diameter,    .     360 

Diameter  of  fire  box  and  grate,        .        »        ....  .         6      ft. 

Distance  of  grate  to  lower  tube  sheet,     .        .        .        .  .         3  ft.  6  in. 
Width  of  air  spaces  and  metal  bars  in  grates,            Air  1-2  in.,  metal  5-8  in. 

Area  of  water-heating  surface,         .        .        .        •  •>'     .  .2,521      sq.ft. 

Area  pf  steam-heating  surface,        . 880      sq.ft. 

Area  of  total  heating  surface,  .        .        .        .'        .        .  .3,401      sq.ft. 

Area  of  grate  surface,       .        .        .  .    '    .        .  .,      56.7.  sq.  ft. 

Area  through  tubes,  .        .-       .        :,'      .        .  ^      .        .  .         8      sq.ft. 

Ratio  of  water-heating  surface  to  grate  surface,     .        »  .  •       44.5  to  1 

Katio  of  steam-heating  surface  to  grate  surface,    .        .  *  '    15.7  to  1 

Ratio  of  total  heating  surface  to  grate  surface,      .        .  .       60.2  to  1 

Ratio  of  grate  surf  ace  to  tube  area,         .        .        .      ;•  .        7.1  to  1 


BOILER  No.  60. 


209 


Boiler  No.  60  consists  of  a 
plant  of  two  vertical  boilers, 
the  general  features  of  which 
are  shown  in  elevation  in  the 
following  cut.  These  boilers 
are  of  the  fire  box  type  and 
they  contain  a  large  area  of 
heating  surface,  the  propor- 
tion of  which  to  grate  surface 
is  60.2  to  1.  One  quarter  of 
this  surface  is  steam  heating 
surface.  There  is  no  brick 
work  about  the  setting,  except 
the  brick  ash  pit  which  sup- 
ports the  boiler.  The  outside 
of  the  shell  is  protected  by  a 
covering  of  asbestos  board  and 
hair  felting.  The  interior 
surfaces  of  the  boiler  were 
free  from  scale. 


60 


BOILER    No.    60,    VERTICAL     ELEVA- 
TION AND  SECTION. 


210  BOILEE    TESTS. 

Results  of  Test,  Boiler  No.  60. 

Test  No.  123. 

Manner  of  start  and  stop,        ,. Thin  tire. 

Kind  of  run, Ordinary. 

Duration, .        .        .         10.3  hrs. 

Coal  consumed,  dry  (including  wood  equivalent),          .    7,588  Ibs. 

Percentage  of  ash,    . 7.7     per  cent. 

Water  evaporated, 81,730  Ibs. 

Coal  per  hour, ,739.3  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .         .        .  ^     .         13  08  Ibs. 

Water  per  hour, . .'  •     .    7,962  8  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,     3  2  Ibs. 

Horse-power  developed, 243.1          H.  P. 

Boiler  pressure, 46.4  Ibs. 

Temperature  of  feed-water, 186  deg. 

Temperature  of  escaping  gases,       .        .        .        .         .427  deg. 

Number  of  degrees  of  superheating,        ....         18  deg. 

Draught  suction, 0.28  in. 

Water  per  pound  of  coal,          ......         10.77  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,     .         11.34  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  12.29  Ibs. 

The  test  on  Boiler  No.  60  shows  the  performance  of  a  well 
proportioned  vertical  tubular  boiler,  using  Cumberland  bitum- 
inous coal.  The  conditions,  both  in  the  matter  of  proportions 
of  the  boiler,  and  the  character  of  the  work  done  during  the 
test,  are  favorable  to  economy.  The  proportion  of  water- 
heating  surface  to  grate  surface  is  as  large  as  good  practice 
in  horizontal  boilers  requires  ;  there  is  a  considerable  amount 
of  steam-heating  surface ;  there  is  a  minimum  chance  for 
external  radiation ;  there  are  no  avenues  for  the  entrance  of 
air  except  those  provided  in  the  fire-door ;  and  during  the  test 
the  rate  of  coal  consumption  was  sufficient  to  secure  excellent 
combustion. 

The  result  of  the  test  bears  out  the  expectations  which  these 
favorable  conditions  justify.  If  an  allowance  be  made  for  the 
superheated  condition  of  the  steam,  the  equivalent  evaporation 
per  pound  of  combustible  from  and  at  212  degrees  becomes 
12.40  pounds,  and  the  high  character  of  the  economy  thus 
shown  needs  no  comment. 


BOILEE   No.  61. 


211 


Boiler  No.  61. 

Kind  of  boiler,    .        .  '•'.  .     •-.•."       . 

Number  in  use,    .         ,         .     -   .        .        . 
Horse-power  (  basis  12  square  feet  ),         .        . 

Kind  of  coal, ; 

Age,      .        .        .        .        ........ 


Cast-iron  sectional. 
One. 

Thirty-seven. 
Anthracite  broken. 
Ten  years. 


Boiler  No.  61  consists  of  a  number  of  hollow  cast  iron 
sections  of  spherical  form  communicating  with  each  other,  the 
lower  sections  being  filled  with  water  and  the  upper  ones 
furnishing  steam  space.  The  products  of  combustion  encircle 
both  the  upper  and  lower  sections,  and  the  boiler  is  thus  made 
a  superheating  boiler.  The  general  features  of  the  boiler  are 
shown  in  the  following  cut. 


BOILER  No.  61,  LONGITUDINAL  SECTION. 


212 


BOILER    TESTS. 


Dimensions  of  Boiler  No.  61. 

Number  of  sections  5x76, 

Area  of  total  heating  surface,        ..     ,  . 
Area  of  grate  surface,       ....      .... 

Area  through  flue,      .        .        .        ..... 

Ratio  total  heating  surface  to  grate  surface,    . 

Ratio  of  grate  to  flue, 

Chimney  height,         .    .     .,..,;-.     .        ..      ; . 


Area  of  water-heating  surface,  square  feet, 
Area  of  steam-heating  surface,  square  feet, 
Ratio  of  water-heating  surface  to  grate, 


Test  No.  124. 
321 
122 
19.7  to  1 


380 

443       sq.  ft. 
16.29  sq.  ft. 
.97  sq.  ft. 
27.2  to  1 
16.8  to  1 
100       ft. 
Test  No.  125. 
221 
222 
13.6  to  1 


Results  of  Tests,  Boiler  No.  61. 


Test  No.  124.       Test  No.  125. 


Duration,      hrs. 

11 

11 

Coal  consumed,    Ibs. 

1,600 

1,579 

9.1 

10 

12,817 

12,434 

Coal  per  hour,      ......  Ibs. 

145.5 

143.5 

Coal  per  hour  per  square  foot  of  grate,     .  Ibs. 

8.9 

8.9 

Water  per  hour,  Ibs. 

1,165.2 

1,130.4 

Water  per  hour  per  square  foot  of  water-heat- 

ing surface,   .        .        .        »  v%  ''•••'      .  Ibs. 

3.6 

5.1 

Horse-power  developed,      .        .       '^  .      H.  P. 

37.5 

36.6 

Boiler  pressure,  .        .                 »        .        .   Ibs. 

28.3 

28.3 

Temperature  of  feed-water,       **    -*•;  •     .  deg. 

123 

117 

Temperature  of  escaping  flue  gases,  .        .  deg. 

575 

540 

Number  of  degrees  of  superheating,          .  deg. 

25 

153 

Water  per  pound  of  coal,    ....  Ibs. 

8.01 

7.87 

Water  per  pound  of    coal    from  and  at  212 

degrees,         ......  Ibs. 

8.90 

8.79 

Water  per  pound  of  combustible  from  and  at 

9.79 

9.78 

NOTE.  —  The  tests  commenced  with  a  banked  fire,  and  ended  24  hours  afterward 
with  the  fire  in  practically  the  same  condition. 

The  special  object  of  the  tests  on  Boiler  No.  61  was  to 
determine  its  performance  as  a  superheating  boiler  with  two 
widely  different  amounts  of  superheating.  The  variation  in 
superheating  was  obtained  by  carrying  the  water  at  two 
different  heights,  the  two  points  being  indicated  in  the  cut. 
On  the  first  test  the  superheating  amounted  to  25  degrees, 
while  on  the  second  test  it  amounted  to  153  degrees.  In  spite 
of  the  wide  difference  in  the  quality  of  the  steam,  the  evapora- 
tion per  pound  of  combustible  was  the  same  in  both  cases. 


BOILER  No.   62. 


213 


The  ratio  of  water  heating  surface  to  grate  surface  in  this 
boiler  is  small,  and,  as  a  consequence,  the  products  of  com- 
bustion escape  to  the  chimney  at  a  high  temperature,  and  the 
economic  result  is  inferior  to  that  obtained  where  these  condi- 
tions are  more  favorable. 

Boiler  No.  62. 

Kind  of  boiler,         .        .        ,        .        .        .     Cast-iron  sectional. 
Number  used,  .        .        .        »        ,        .         .     Ten. 
Horse-power  (collective,  basis  12  square  feet),  Four  hundred  and  sixty. 
Kind  of  coal,    .        .        .        .,    "  *        •        •     Anthracite  Chestnut  No.  2. 
Ai?e,       .-- .  *     i   ,„..,••.-•.,;,;,•.:     .  •*•     .     Twelve  years. 


BOILER  No.  G2,  GROUND  PLAN  SHOWING  LOCATION  OF  BOILERS 
AND  FLUE  HEATER. 

Boiler  No.  62  embraces  a  plant  of  eight  cast-iron  sectional 
boilers,  a  ground  plan  of  which  is  shown  in  the  following  cut. 
The  individual  boilers  are  of  the  same  general  form  as  that 
shown  in  elevation  in  the  cut  of  Boiler  No.  61.  In  these 
boilers  a  line  of  horizontal  plates,  or  shields,  is  introduced 
between  the  sections,  along  the  water  line,  in  order  to  separate 
the  space  above  the  water  line  from  that  below  it,  and  cut  off 
the  steam  heating  surface.  The  total  area  of  surface  both 

o 

above  and  below  the  water  line  amounts  to  850  square  feet  in 
each  boiler,  and  of  this,  approximately  548  square  feet  lies 
below  the  shields,  The  upper  ends  of  the  boilers  are  not 
sufficiently  covered  with  brick  work  to  wholly  protect  the  iron 
work  of  the  upper  sections.  The  brick  walls  of  the  settings 
are  unsound,  and  many  small  openings  are  thus  provided  for 


214 


BOILER    TESTS. 


the  entrance  of  air  into  the  furnace  space.  The  plant  is  fitted 
with  a  flue  heater,  located  at  the  point  shown  in  the  cut.  The 
heater  consists  of  a  cluster  of  vertical  cast-iron  pipes  arranged 
in  the  same  manner  as  that  connected  with  Boiler  No.  33. 

Dimensions  of  Boiler  No.  62. 

Area  of  heating  surf  ace  (  below  shields  ),  .  .  .  .5,480  sq.ft. 
Area  of  grate  surface,  .  .  .  .  .  .  .  .  259  sq.ft. 

Area  through  flue, .         .         .        18     sq.  ft. 

Area  through  tubes,  .         .         .                 .         *         .         .         .        22.5  sq.  ft. 
Height  of  chimney,   .         .                  .  \              .      •  .         .         .      110     ft. 
Width  of  air  spaces  and  metal  bars  in  grates,          .  \     -.        .      3-8      in. 
Ratio  of  heating  surface  below  shields  to  grate  surface,        .        21.2  to  1 
Ratio  of  total  heating  surface  to  grate  surface,      .    <    .        .       32.8  to  1 
Ratio  of  grate  surface  to  flue  area,           .        .'       .        ...        11.5  to  1 
Area  or  heating  surface  in  flue  heater, 1,280     sq.  ft. 

Results  of  Tests,  Boiler  No.  62. 


Test  No.  126. 

Test  No.  127 

Conditions  as  to  flue  heater,                               < 

Heater  in 

Heater  not 

\ 

use. 

in  use. 

Manner  of  start  and  stop  and  kind  of  run, 

Ordinary. 

Ordinary. 

Duration,      .......  hrs. 

11 

11 

Coal  consumed,    dry   (  including  wood  equiv- 

alent )  Ibs. 

25,500 

28,486 

Percentage  of  ash,      ....  per  cent. 

15.5 

15.2 

Water  evaporated,       .....   Ibs. 

192,802 

196,458 

Coal  per  hour,      .        .        .        .        .        .  Ibs. 

2,272.1 

2,589.5 

Coal  per  hour  per  square  foot  of  grate,        Ibs. 

9.2 

10.0 

Water  per  hour,  Ibs. 

19,171 

20,538 

Water   per  hour  per  square    foot  of  heating 

surface,         Ibs. 

2.5 

2.6 

Horse-power  developed,      .        .        .         H.  P. 

5G8 

608.6 

Boiler  pressure,  ......   Ibs. 

82 

82 

Temperature  of  feed-water  entering  heater,deg. 

111 

- 

Temperature  of  feed-water  entering  boiler,deg. 

1G9 

112 

Temperature  of  escaping  gases  leaving  boiler, 

deg. 

403 

— 

Temperature  3f  escaping  gases  entering  chim- 

ney,                                                            deg. 

299 

434 

Number  of  degrees  flue  heater  added  to  water, 

deg. 

58 

— 

Number  of  degrees  flue  heater  reduced  gases, 

deg. 

104 

— 

Water  per  pound  of  coal,  ....   Ibs. 

7.53 

6.89 

Water  per  pound  of  coal  from  and  at  212  de- 

grees,    .......  Ibs. 

— 

7.85 

Water  per  pound  of  combustible  from  and  at 

212  degrees,           .        .        .        .        .   Ibs. 

•— 

9.26 

NOTE.  —  The  coal  in  Test  No.  126  when  fired  contained  5.5  per  cent,  of  moisture  ;that 
in  No.  127  contained  3.G  per  cent. 


BOILER  No.  62.  215 

The  tests  on  Boiler  No.  62  had  for  a  principal  object  the 
the  determination  of  the  economy  produced  by  the  use  of  a 
flue  heater.  Test  No.  126  was  made  with  the  flue  heater  in 
use,  and  Test  No.  127  with  the  heater  shut  off,  and  the  gases 
passing  to  the  chimney  through  the  direct  flue.  The  use  of 
this  apparatus  secured  a  reduction  of  104  degrees  in  the  tem- 
perature of  the  waste  gases,  or  135  degrees,  when  referred  to 
the  temperature  obtained  on  Test  No.  127.  The  heater  in- 
creased the  temperature  of  the  water  58  degrees,  the  initial 
temperature  being  111  degrees.  The  water  evaporated  per 
pound  of  coal  was  increased  by  using  the  heater  from  6.89  to 
7.53,  or  0.64  pounds,  and  this  represents  a  gain  of  9.3  per 
cent.  When  the  same  heater  was  supplied  with  water  at  200 
degrees,  the  flue  gases  entering  at  380  degrees,  the  tempera- 
ture of  the  water  was  raised  25  degrees.  Looking  at  the 
general  results  of  Test  No.  127,  it  appears  to  be  little  better 
than  that  obtained  on  the  plain  cylinder  boiler,  Test  No.  94, 
in  which  the  temperature  of  the  waste  gases  was  higher  to  the 
extent  of  133  degrees.  It  appears  that  the  temperature  of  the 
gases,  which  was  434  degrees  on  Test  No.  127,  does  not 
represent  the  true  loss  at  the  chimney,  owing  to  the  leakage  of 
a  large  amount  of  air  into  the  furnace.  As  an  indication  of  the 
extent  to  which  this  leakage  occurred,  it  may  be  said  that  the 
draught  suction  in  the  main  flue,  amounting  to  0.65  of  an  inch 
water  pressure,  was  reduced  to  0.34  of  an  inch  in  the  furnace 
of  one  of  these  boilers,  with  the  fire-doors  and  ash-pit  doors 
tightly  closed  and  the  damper  wide  open.  Had  there  been  no 
leakage,  the  full  suction  of  the  main  flue  would,  under  these 
circumstances,  have  been  secured  at  the  furnace. 

Boiler  No.  63. 

Kind  of  boiler, Cast-iron  sectional. 

Number  used,  .        .  .,.'.'        .  Two. 

Horse-power  (  collective,  basis  12  square  feet  ),    .  One  hundred  and  forty. 

Kind  of  coal, Bituminous  Cambria. 

Age, ..•".'.  ...        .        .  Fifteen  years. 

Boiler  No.  63  embraces  a  plant  of  two  sectional  boilers  set 
in  one  battery  of  brick  work.  The  general  form  of  the  boilers 


216  BOILER    TESTS. 

and  the  arrangement  of  the  setting  are  the  same  as  shown. in 
the  cut  of  Boiler  No.  61.  The  whole  exterior  of  the  various 
sections  is  exposed  to  the  heat,  and  the  surface  above  the 
water  line  is  thus  made  steam  heating  surface.  The  boilers 
had  been  in  use  several  years,  and  their  interior  surfaces  had 
become  coated  to  some  extent  with  scale,  which  had  never 
been  removed. 

Dimensions  of  Boiler  No.  63. 

Area  of  water-heating  surface,  .  .  -•'.  .  -.  .  1,687  sq.  ft. 
Area  of  steam-heating  surface,  ......  562  sq.  ft. 

Area  of  grate  surface 69.7  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates.          .        .        .1-2     in. 
Ratio  of  water-heating  surface  to  grate  surface,     .        .        .        24.2  to  1 
Ratio  of  steam-heating  surface  to  grate  surface,   li.  ^  .>•        .         8     to  1 

Results  of  Test,  Boiler  No.  63. 

Test  No.  128. 
Manner  of  start  and  stop  and  kind  of  run,      .        .        .        .          Ordinary. 

Duration,    ..........         10  4  hrs. 

Coal  consumed,  dry  (including  wood  equivalent),          .    6.580  Ibs. 
Percentage  of  ash,    .      .  .    .     .        .        .        ...•'.         12.4    percent. 

Water  evaporated,     .......        .        .        .        .           48,050  Ibs. 

Coal  per  hour, .        .       660.2  Ibs- 

Coal  per  hour  per  square  foot  of  grate,    .        .        .        .           9.47  Ibs. 

Water  per  hour, 4.641.9  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,        2.8  Ibs. 

Horse-power  developed 155.2  H.  P. 

^Boiler  pressure.          ........         54.7  Ibs. 

Temperature  of  feed-water,      .        .        .        .        .        .         92.6  deg. 

Temperature  of  escaping  gases,        .        ...        .        .       462  deg. 

Number  of  degrees  of  superheating,        .        ...         29  cleg. 

Draught  suction, 0.09  in. 

Water  per  pound  of  coal,         .'.        .        .        .        .        .           7.30  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .           8.41  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,       9.61  Ibs. 
.NOTE.  —  The  coal  when  fired  contained  3.7  per  cent,  of  moisture. 

The  test  on  Boiler  No.  63  shows  the  performance  of  a  cast- 
iron  sectional  boiler,  using  Cambria  bituminous  coal.  This 
boiler  worked  under  many  unfavorable  conditions,  and  the 
economic  result  of  the  test  is  inferior  to  the  best  practice. 
The  ratio  of  water  heating  surface  to  grate  surface  is  small, 
and  the  efficiency  of  this  surface  had  become  reduced  by  age, 
so  that  the  escaping  gases  passed  to  the  chimney  at  a  high 


BOILER  No.  64.  217 

temperature.  The  actual  loss  due  to  the  waste  heat  is  no 
doubt  greater  than  would  appear  from  the  simple  indication  of 
temperature,  on  account  of  the  facility  with  which  air  finds 
entrance  into  the  furnace  in  this  form  of  boiler,  especially  in 
the  case  under  consideration,  where  the  brick  work  ot  the 
setting  had  become  deteriorated.  The  steam  heating  surface 
produced  a  superheating  amounting  to  29  degrees.  The 
boilers  developed  somewhat  more  than  their  rated  capacity, 
with  a  draught  suction  of  only  .09  inch. 

Boiler  No.  64. 

Kind  of  boiler,  .        .    •-..        .        .        .-      Water-tube. 

Number  used,     .  .     ...        .        .        ...       One. 

Horse-power  (basis  12  square  feet),       .        Seventy. 

Kind  of  coal,      .        .        .        ...        Anthracite  Lehigh,  chestnut. 

Age,    .        .        .        .        .        .        >'.-  -.*        Six  months. 

Boiler  No.  64  is  a  water  tube  boiler,  the  general  features 
and  the  manner  of  setting  of  which  are  shown  in  longitudinal 
section  in  the  following  cut.  This  boiler  consists  essentially 
of  a  cluster  of  parallel  tubes,  connected  at  either  end  through 
headers,  with  a  drum  above.  The  water  fills  the  whole  up  to 
about  the  middle  of  the  drum,  and  the  arrangement  is  such 
that,  in  process  of  operation,  a  circulation  is  established 
through  the  tubes,  the  water  starting  from  the  back  end  of  the 
drum,  thence  passing  into  the  tubes  and  returning  through 
them  to  the  front  end.  The  products  of  combustion  on  leav- 
ing the  furnace  pass  around  and  between  the  tubes,  taking  a 
direction  at  right  angles  to  their  length.  Their  course  lies 
successively  through  three  compartments,  into  which  the 
space  is  divided  by  means  of  partitions.  The  lower  half  of 
the  drum  is  exposed  to  the  heat,  and  the  upper  half  is  covered 
with  brick  work.  The  brick  side  walls  of  the  furnace  in  this 
case  are  provided  with  perforated  plates,  through  which  air  is 
admitted  above  the  fuel,  the  air  first  passing  back  and  forth 
through  ducts  in  the  walls. 


218 


BOILER    TESTS. 


diameter,      .    . 
*s  in  grates,       .  , 

...          42 
10 
30 
15  ft.,  9 
840 
.         .           225 
.      ,/..        1-4 
-             4 

ft. 
in. 
in. 
sq.  ft. 
sq.  ft. 
in. 
sq.  ft. 

surface, 

'.       .'.          57 
.   '      «           37.3 
..         .             5.6 

ft. 
to  1 
to  1 

BOILER  No.  64,  LONGITUDINAL  SECTION. 

Dimensions  of  Boiler  No.  64. 
Number  of  tubes  4  inches  outside  diameter, 
Length  of  tubes,      .        v- 
Diameter  of  drum  (  one  ), 
Mean  length  of  drum, 
Area  of  heating  surface, 
Area  of  grate  surface,    . 
Width  of  air  spaces  and  metal  bars  in  grates, 
Area  through  flue  and  chimney, 
Height  of  chimney, 

Ratio  of  heating  surface  to  grate  surface, 
Ratio  of  grate  to  flue  area,     . 

Results  of  Test,  Boiler  No.  64. 

Test  No.  129. 

Manner  of  start  and  stop  and  kind  of  run,              .        .  .  Ordinary. 

Duration,  .  .     ..'•    y  t    .        ./....        .        .  10.7  hrs. 

Coal  consumed,  ( including  wood  equivalent),       .        .  2,252  Ibs. 

Percentage  of  ash,     .        .        .    ^    .-.'.-,        .  14  percent. 

Water  evaporated,     .        .      .......        •        »        •  19,178  Ibs. 

Coal  per  hour,    .-..,.    v  ..    v.        .        .  209.5  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   ....  9.3  Ibs. 

Water  per  hour,         .        .        .        .       ".        .        .        .  1,784  Ibs. 

Water  per  hour  per  square   foot  of    heating  surface,  2.1  Ibs. 

Horse-power  developed,    .        •        «        .        .        .        .  54.8  H.  P. 

Boiler  pressure,          .        .        .        .        .        .        .        .  89  ibs. 

Temperature  of  feed-water 180  deg. 

Temperature  of  escaping  gases 337  deg. 


BOILEE  No.   05. 


2!  9 


Draught  suction,         ........         0.09  in. 

Water  per  pound  of  coal,           ......           8.52  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,       .        .9.12  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,  10.61  Ibs. 

The  test  on  Boiler  No.  64  shows  the  performance  of  a  water 
tube  boiler,  working  under  somewhat  unfavorable  conditions 
for  the  best  results.     The  slow  rate  of  combustion  employed, 
and  the  admission  of  air  above  the  fuel,  the  fuel  being  in  this 
case   anthracite  coal,  were  no  doubt  the  cause  of  some  loss. 
As  the  results  stand  they  do  not  differ  materially  in  point  of 
economy  from   those    obtained    from   the    horizontal    tubular 
boilers,  No.  13,  No.  14,  and  No.  15, -made  with  a  similar  class 
of  coal. 

Boiler  No.   65. 
Kind  of  boiler,         ...        .        .        Water-tube. 

Number  used,  .        .  .      .       .".        .        .        Four. 

Horse-power  (  collective,  basis  12  sq.  ft.  ),    Four  hundred  and  sixty-eight. 
Kind  of  coal,    .        .        .  ...-    ;.        Anthracite  Shamokin,  pea. 

Age,          .   •'  '.  .     .        .        .       "*'/•  .        Three  years. 

Boiler  No.  65  embraces  four  water  tube  boilers  of  the 
general  form  shown  in  longitudinal  section  in  the  following 
cut.  They  are  set  in  two  independent  batteries  of  brick  work, 
each  embracing  two  boilers.  The  main  flue  behind  the  boilers 
is  provided  with  a  small  flue  heater,  consisting  of  wrought 
iron  pipes,  having  an  exposed  surface  amounting  to  515 
square  feet. 


BOILER  No.  05,  LONGITUDINAL  SECTION. 


220  BOILER    TESTS. 

Dimensions  of  Boiler  No.  60. 
Number  of  tubes  (  collective  )  4  inches  outside  diameter,       .     256 

Length  of  tubes, 18      ft. 

Diameter  of  drums  (four),      .        .        .        .        .        .        .      36      in. 

Mean  length  of  drums, 17  ft.  6      in. 

Area  of  heating  surface,   ........  5,614     sq.  ft. 

Area  of  grate  surface, 141.7  sq.  ft. 

Area  through  flue,      .        .        .      ' ."    ' 18.5  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,        Air  5-16  in.,  metal  7-16  in. 
Ratio  of  heating  surface  to  grate  surface,        .        .        .        .      40     to  1 
Ratio  of  grate  surface  to  flue  area,       .  -.  -,     .        .        .        .        7.2  to  1 

Results  of  Test,  Boiler  .Vo.  65. 

Test  No.  130. 
Manner  of  start  and  stop  and  kind  of  run,      .        .        .        .         Ordinary. 

Duration,    .        .        .        .       ..,»,•.,      .      ......  ,;     ..        .        .11  hrs. 

Coal  consumed,  dry  (  including  wood  equivalent  ),          .    19,043  Ibs. 

Percentage  of  ash,     .        .        .        .        .        .        ...  17.4  percent. 

Water  evaporated,      .        .        .        .        ...        .  161,656  Ibs. 

Coal  per  hour,    .        .        .        .    '"  V       .        .        .        .      1,731.2  Ibs. 

Coal  per  hour  per  square  foot  of  grate,    .       ".        .        .        .12.2  Ibs. 

Water  per  hour,          .        .        .        .        .     .    .        .        .    14,696  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,       &*.    .>  :  2.5  Ibs. 

Horse-power  developed,    .        ...      .        .        .        ..       .         474.4        H.  P. 

Boiler  pressure,          .        .        .        .   '     .        .        .        ./      101.2  Ibs. 

Temperature  of  feed-water  leaving  heater,    '.*--'.*       .          145.3          deg. 
Temperature  of  escaping  gases,      -4-.,      .,;    \?5'    :.r:''i"       353  cleg. 

Draught  suction,        .        .        ...     ,.\.       ..      j.        &\     .    0.29        in. 

Percentage  of  moisture  in  steam,  .  .  .  ".  .  .  0.6  per  cent. 
Water  per  pound  of  coal,  'V  %  "  '«  '  ,.:  ;.  .  .  8.49  Ibs. 
Water  per  pound  of  coal  from  and  at  212  degrees,  .  .  9.45  Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,  .  11.44  Ibs. 
NOTE.  — The  coal  when  fired  contained  5  per  cent,  of  moisture. 

The  test  on  Boiler  No.  65  shows  the  performance  of  a  water 
tube  boiler  with  one  of  the  small  grades  of  anthracite  coal. 
The  conditions  with  respect  to  capacity,  rate  of  combustion 
and  temperature  of  escaping  gases,  are  all  favorable,  and  an 
exceedingly  high  evaporative  result,  based  on  combustible,  is 
secured.  A  subsequent  test  was  made  when  only  three  boilers 
were  in  use,  developing  about  the  same  total  power.  The 
rate  of  combustion  was  15.7  pounds,  the  percentage  of  ash 
15.8  per  cent.,  the  temperature  of  the  feed  water  156.7 
degrees,  and  the  temperature  of  the  escaping  gases  389 


BOILEE  No.  66. 


221 


degrees.  The  evaporation  was  8.48  pounds  of  water  per 
pound  of  coal,  and  11.08  pounds  of  water  from  and  at  212 
degrees  per  pound  of  combustible. 

The  temperature  of  the  escaping  gases  was  obtained  at  a 
point  between  the  flue  heater  and  the  chimney.  The  heater 
added  18  degrees  to  the  temperature  of  the  water  on  Test 
No.  130,  that  on  entering  the  heater  being  126.8  degrees. 

Boiler  No.  66. 

Kind  of  boiler,         .       '.'./..   ....     .,-  .  Water  tube. 

Number  used,   .        .        .        .        .        .  .  One. 

Horse  power  (  basis  12  square  feet),       .  .  One  hundred. 

Kind  of  coal,    .         .        .        .        .        .  .  Anthracite  Lchigh,  broken. 

Age,           .        .        .        .       ..       •••'.•  .  Six  months. 

Boiler  No.  66  is  a  water  tube  boiler,  having  the  general 
features  shown  in  longitudinal  section  in  the  following  cut. 


BOILER  No.  66,  LONGITUDINAL  SECTION. 
Dimensions  of  Boiler  No.  66. 


Number  of  tubes,         .        .        . 
Length  of  tubes,          ..  ;  •••-  . 
Diameter  of  drum,       .                 .        . 
Mean  length  of  drum,      ^  ?V             '  . 

.    54 
.         .         .         .     18      ft. 
.     36      in. 
.     17  ft.  6      in. 
1,196      sq.  ft. 

Area  of  grate  surface,        .        .        .'•  . 

.     28.7  sq.  ft. 

222  BOILER    TESTS. 

Area  through  flue, .        .      9.8  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  .        Air  3-8  in.,  metal  1-4  in. 
Ratio  of  heating  surface  to  grate  surface,         ....     40.3  to  1 
Ratio  of  grate  to  flue  area,          .        .        .        .        .        .        .      G.I  to  1 

Results   of   Test,   Boiler   No.   66. 

Test  No.  131. 
Manner  of  start  and  stop  and  kind  of  run,      ....          Ordinary. 

Duration, 10.5  hrs. 

Coal  consumed, 5,553  Ibs. 

Percentage  of  ash,     .         .        .        .        .        .        .        .        .9.2  per  cent. 

Water  evaporated, 45,803  Ibs. 

Coal  per  hour, 528.8  Ibs. 

Coal  per  hour  per  square  foot  of  grate,   ....  17.8  Ibs. 

Water  per  hour 4,362.2  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,         .        .     3.6  Ibs. 

Horse-power  developed,     .        .        .        .        .        .        .         133.1         H.  P. 

Boiler  pressure, 73  Ibs. 

Temperature  of  feed  water, 183  deg 

Temperature  of  escaping  gases,        .....         540  deg. 

Water  per  pound  of  coal, 8.24          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .        .    8.77          Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,     .    9.68          Ibs. 

The  test  on  Boiler  No.  6()  shows  the  performance  of  a  water 
tube  boiler,  which  had  favorable  proportions  and  used  a 
standard  grade  of  coal,  but  which  was  operated  under  unfavor- 
able conditions  in  respect  to  capacity.  The  rate  of  combustion 
was  17.8  pounds  of  coal  per  square  foot  of  grate  per  hour, 
which,  for  the  class  of  fuel  used,  is  too  high  for  economical 
work.  The  horse  power  developed  was  one-third  above  the 
rating.  The  evaporative  result  is  low  compared  with  the  best 
practice,  and  the  high  temperature  of  the  escaping  gases, 
which  was  540  degrees,  reveals  the  cause  of  the  inferior  per- 
formance. At  the  close  of  the  test  it  was  found  that  some  of 
the  partitions  were  disarranged,  thereby  allowing  at  certain 
points  a  free  passage  of  the  products  of  combustion  along  the 
tubes  to  the  flue.  This  defect  was  largely  the  cause  of  the 
high  temperature  of  the  gases. 

Boiler  No.  67. 

Kind  of  boiler,   .         ...        .        .        Water  tube. 

Number  used, One. 

Horse-power  (basis  12  square  feet),        Seventy. 

Kind  of  coal, Anthracite  Lehigh,  chestnut  No.  2. 

Age,     .        .        .        .        .        .        .        Six  months. 


BOILEK  No.   67.  223 

Boiler  No.  67  is  a  water  tube  boiler,  having  the  general 
features  shown  in  the  cut  of  Boiler  No.  66.  It  is  of  compara- 
tively small  size,  having  only  42  tubes,  and  it  is  connected 
with  a  chimney  which  is  deficient  in  draught  power. 

Dimensions  of  Boiler  No.  67. 

Number  of  'tubes  4  inches  outside  diameter,  . .        .  .  42 

Length  of  tubes,               .    ^  .        .,      •    "     •  •        •  •  1G     ft- 

Area  of  heating  surface,         .      ' '.        .        .  .    »    .  .  839     sq.ft. 

Area  of  grate,         .        .        .        ...       •..  '.       -..  _  V !-.  23     sq.  ft- 

Area  through  flue,            .        .        .        •'      »  v       •  •  5-3  sq.ft. 

Width  of  air  spaces  and  metal  bars  in  grates,  Air  5-16  in.,  metal  1-2  in. 

Height  of  chimney,          .'      '.'•..     .;.         ..  .         .  .  60     ft. 

liatio  of  heating  surface  to  grate  surface,     .  .      • .  •  .  36.5  to  1 

Ratio  of  grate  surface  to  flue  area,         .        *  .        .  .  4.3  to  1 

Results  of  Test,  Boiler  No.  67. 

Test  No.  132. 

Manner  of  start  and  stop,          ...        .        .        .  .         Ordinary. 

Kind  of  run.       .        .        .        .        .        .        .    '    .        .  .     Continuous. 

Duration,                             '. 8.3  hrs. 

Coal  consumed,  dry  (  including  wood  equivalent  ),           .  1,576               Ibs. 

Percentage  of  ash,     .     .-  .        .      . .                 ...  14.7  percent. 

Water  evaporated,     .        .     '.        .        .        .        .        .  11,292              Ibs. 

Coal  per  hour,    .        .        .        »        .  '     .        .        .        .  189.2            Ibs. 

Coal  per  hour  per  square  foot  of  grate,   .       ...        .  8.2            Ibs. 

Water  per  hour,          .        ...        .     •  .        .        .        .  1,355.5            Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,        .  1.6            Ibs. 

Horse-power  developed,    .        »        .-.     ".        .        .        .  47.2         H.  P. 

Boiler  pressure,          .        .        .        .        .        .        .        .  104               Ibs. 

Temperature  of  feed-water,     .        .        .     /.        .        .  68              cleg. 

Temperature  of  escaping  gases,        .        .        .        .      " .  360              deg. 

Draught  suction,        .        .        .        ,        .        .        .  0.2              in. 

Water  per  pound  of  coal,                   .        .        ....  7.16          Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .  8.52          Ibs. 
Water  per  pound  of  combustible  from  and  at  212  degrees,    .  10.00          Ibs. 

The  test  on  Boiler  No.  67  shows  the  performance  of  a  small 
water  tube  boiler,  using  one  of  the  low  grades  of  anthracite 
coal.  The  result  obtained,  which  was  10  pounds  of  water 
from  and  at  212.  per  pound  of  combustible,  is  somewhat 
inferior  to  good  practice.  Test  No.  47,  made  with  a  similar 
coal  on  a  horizontal  tubular  boiler,  gave  10.72  pounds  and 
Test  No.  58,  10.78  pounds.  In  the  case  under  consideration 
the  boiler  had  plenty  of  heating  surface,  and  the  heat  was  well 


224  BOILER    TESTS. 

absorbed,  as  the  comparatively  low  flue  temperature  indicates. 
The  rate  of  combustion  is  somewhat  low  for  the  water  tube 
type  of  boiler,  the  draught  being  deficient,  and  this,  coupled 
with  the  possibility  of  an  inferior  quality  of  fuel  used 
furnishes  a  partial,  and  perhaps  a  full  explanation  of  the 
inferior  character  of  the  result. 

Boiler  No.  68. 

Kind  of  boiler Water  tube. 

Number  used Two. 

Horse-power  (  collective,  basis  12  sq.  ft.  ),  Two  hundred  and  sixty. 

Kind  of  coal, George's  Creek  Cumberland. 

Age, Two  years. 

Boiler  No.  68  consists  of  a  plant  of  two  water  tube  boilers 
of  the  form  shown  in  longitudinal  section  in  the  cut  of  Boiler 
No.  64.  The  brick  side  walls  of  the  furnaces  are  fitted  with 
perforated  tiles,  through  which  air  is  admitted  over  the  fuel, 
as  shown  in  the  cut  referred  to.  This  plant  is  provided  with 
a  flue  heater,  the  location  of  which  with  reference  to  the  boilers 
and  chimney  is  shown  in  the  following  cut.  The  heater  con- 
sists of  a  cluster  of  vertical  cast  iron  pipes,  similar  to  that  in 
use  on  Boiler  No.  33.  The  heating  surface  exposed  by  these 
pipes  is  about  half  as  much  as  the  total  heating  surface  of  the 
two  boilers. 

Dimensions  of  Boiler  No.  68. 

Number  of  tubes  4  inches  outside  diameter,    ....     144 

Length  of  tubes, 18     ft. 

Diameter  of  drums  (2), 36     in. 

Mean  length  of  drums, 17  ft.,  6     in. 

Area  of  heating  surface, 3,126      sq.ft. 

Area  of  grate  surface,       .        .        .        .        ..        ...:*.-.       50      sq.ft. 

Area  through  flue,      .        .        .        .        .v       .        .        .. ,     ..       11      sq.ft. 

Height  of  chimney,   .-  '     .'    '  .  y. .  .        •        .'.'•;'*''.       80      ft. 
Width  of  air  spaces  and  metal  bars  in  grates,  Air  1-2  in.,  metal  11-16  in. 
Ratio  of  heating  surface  to  grate  surface,        ....       62.5  to  1 

Ratio  of  grate  surface  to  flue  area,  .-,,'»        •        .        •        •         4.5  to  1 
Area  of  heating  surface  in  flue  heater,     ....          1,600     sq.  ft. 


BOILER  No.  68. 


225 


BOILER  No    G8,  GROUND  PLAN  SHOWING  LOCATION  OF  BOILERS  AND 
FLUE  HKATKH. 


226 


BOILER    TESTS. 

Results  of  Tests,  Boiler  No.  68, 


Test  No.  133. 

Test  No.  134. 

Heater  in 

Heater  not 

use. 

in  use. 

Manner  of  start  and  stop  and  kind  of  run. 

Ordinary. 

Ordinary. 

Duration,      ....                 .           hrs. 

11.5 

11.5 

Coal  consumed,   dry  (  including  wood  equiva- 

lent),   .                 .                                  .   Ibs 

8,743 

9,094 

Percentage  of  ash.      ...           per  cent. 

75 

7.7 

Water  evaporated.       Ibs. 

84,078 

82,725 

Coal  per  hour,      .         .         .                 .        .Ibs. 

700.3 

843 

Coal  per  hour  per  square  foot  of  grate.     .  Ibs. 

15  2 

10.8 

Water  per  hour,  ...                 .            Ibs. 

7,310.4 

7,193.2 

Water  per  hour  per  square  foot  of  heating  sur- 

face,          Ibs. 

23 

2.3 

Horse-power  developed,      .        .        .         II.  P. 

247 

243.5 

Boiler  pressure     ......  Ibs. 

08 

07 

Temperature  of  feed-water  entering  heater,  (leg. 

84 

- 

Temperature   of    feed    water  entering   boiler, 

deg. 

190 

82 

Temperature  of  escaping  gases  leaving  boiler, 

deg. 

435 

452 

Temperature  of  escaping  gases  leaving  heater, 

deg. 

279 

_ 

Draught  suction,           in. 

0.25 

0  27 

Percentage  of  moisture  in  steam,          per  cent. 

1.3 

- 

Water  per  pound  of  coal,    ....   Ibs. 

9.G2 

8  53 

Water  per  pound  of  coal    from    and   at    212 

degrees,          ......   Ibs. 

9.95 

Water  per  pound  of  combustible  from  and   at 

212  degrees,  .         ...        .         .   Ibs. 

10.79 

NOTE.  —  The  coal  when  fired  contained  5  per  cent,  of  moisture. 

The  tests  on  Boiler  No.  68  had  for  a  principal  object  the 
determination  of  the  economy  produced  by  the  use  of  a  flue 
heater.  The  heater  was  in  operation  on  Test  No.  133,  and  it 
was  shut  off  on  Test  No.  134,  the  flue  gases  passing  directly 
from  the  boiler  to  the  chimney.  The  use  of  this  apparatus 
secured  an  increase  in  the  temperature  of  the  water  of  19()° — 
84°=  112  degrees,  and  a  reduction  in  the  temperature  of  the 
gases  of  435°  —  279°  =  156  degrees,  resulting  in  an  increase 
in  the  evaporation  per  pound  of  coal  amounting  to  12.8  per 
cent. 

Looking  at  the  general  performance  of  the  boilers,  when 
worked  without  the  heater,  it  appears  that  the  result  secured 
is  much  inferior  in  point  of  economy  to  that  obtained  from  the 


BOILER  No.    68.  227 

best  class  of  shell  boilers.  The  proportion  of  heating  surface 
to  grate  surface  is  ample,  so  also  is  the  rate  of  combustion. 
The  temperature  of  the  escaping  gases  is  not  excessive.  The 
quality  of  the  coal,  judging  from  the  low  percentage  of  ash,  is 
excellent.  With  all  these  conditions,  which  would  ordinarily 
be  considered  favorable,  it  is  difficult  to  assign  a  cause  for  the 
inferior  result,  unless  it  be  the  loss  produced  by  the  admission 
of  air  over  the  fuel  through  the  passages  in  the  walls,  and  that 
which  may  have  entered  through  openings  in  the  brick  work 
due  to  the  somewhat  long  service  to  which  the  boiler  had  been 
subjected.  The  admission  of  air  in  this  manner  makes  the 
actual  loss  from  the  waste  heat  in  the  gases  greater  than  that 
apparently  indicated  by  the  temperature. 

Previous  to  the  introduction  of  the  flue  heater  a  test  was 
made  upon  the  plant  when  the  boilers  had  been  in  use  but  a 
few  weeks,  the  coal  employed  being  Powelton  bituminous 
mixed  with  one-fourth  of  its  weight  of  pea  and  dust  coal. 
The  grate  surface  on  this  occasion  had  a  much  larger  area, 
being  70  square  feet  and  the  proportion  of  heating  surface  to 
grate  surface  was  thereby  reduced  to  44.7  to  1.  The  principal 
results  were  as  follows  : 

Coal  per  hour  per  square  foot  of  grate  surface,       .        .          16.7  Ibs. 

Percentage  of  ash,- 9.0    per  cent. 

Water  per  hour  per  square  foot  of  heating  surface,        .        .  3.7  Ibs. 

Horse-power  developed, 403.3  H.  P. 

Boiler  pressure, 77.0  Ibs. 

Temperature  of  feed-water, 38.0  cleg. 

Temperature  of  escaping  gases, 402.0  cleg. 

Draught  suction, 0.5  in. 

Water  per  pound  of  coal, 9.75  Ibs 

Water  per  pound  of  coal  from  and  at  212  degrees,          .          11.86  Ibs 

Water  per  pound  of  combustible  from  and  at  212  degrees,     13.01  Ibs 
NOTE.-  The  coal  when  fired  contained  4.5  per  cent,  of  moisture. 

This  test  is  remarkable  on  account  of  the  high  character  of 
the  result.  Compared  with  the  later  test  it  shows  the 
effect  which  age  may  produce  upon  the  performance  of  a 
boiler.  Although  the  boiler  developed  nearly  50  per  cent, 
more  than  that  on  test  No.  134,  the  heat  was  so  much 
better  absorbed  by  the  new  and  clean  surfaces  that  the 


228 


BOILEE   TESTS. 


temperature  of  the  gases  was  reduced  to  402  degrees,  which, 
under  the  circumstances,  is  most  favorable  to  economy. 
Futhermore,  the  new  condition  of  the  setting  prevented  the 
introduction  of  unneeded  air,  which  seems  to  have  been  one  of 
the  main  causes  of  the  unfavorable  results  of  the  later  tests. 


Boiler  No.  69. 


Kind  of  boiler,  .      -.        .     *- . 

Number  used,     .        .     .   ,*       .       -. 
Horse-power  (  basis  12  square  feet ), 

Kind  of  coal,      .        .        . 


Age, 


Water  tube. 

One. 

Eighty. 

/  Anthracite  Lackawanna  Chest- 
\     nut  No.  2. 

Three  months. 


Boiler  No.  69  is  a  water  tube  boiler,  having  the  general 
features  shown  in  longitudinal  section  in  the  following  cut. 
It  is  provided  at  the  top  with  three  drums,  14  inches  in 
diameter,  connected  at  the  ends  to  the  tubes  below,  and  these 
are  wholly  enclosed  in  the  chamber  formed  by  the  brick 
setting.  The  water  line  is  carried  to  about  the  central  point 
of  the  drums,  and  the  exterior  surface  above  it  furnishes  a 
small  amount  of  steam  heating  surface. 


BOILER  No.  69,  LONGITUDINAL  SECTION. 


BOILER   No.    69.  229 

Dimensions  of  Boiler  No.  69. 
Number  of  tubes  4  inches  outside  diameter,    ....        48 

Length   of  tubes, 15     ft. 

Diameter  of  drums  (three), 14     in. 

Length  of  drums, 15     ft. 

Area  of  water-heating  surface, 848     sq.  ft. 

Area  of  steam-heating  surface,         .         .        .        .        .        .114     sq.  ft. 

Area  of  total-heating  surface,          .        .        .  .        .962     sq.  ft. 

Area  of  grate  surface, 27     sq.  ft. 

Area  through  flue, 3.7  sq.  ft. 

Height  of  chimney, 70     ft. 

Width  of  air  spaces  and  metal  bars  in  grates,    Air  3-8  in.,  metal  1-2    in. 
Ratio  of  water-heating  surface  to  grate  surface,     .        .         .        31.4  to  1 
Ratio  of  steam-heating  surface  to  grate  surface,     .        .        .         4.2  to  1 
Ratio  of  grate  surface  to  flue  area, 7.4  to  1. 

Results  of  Test,  Boiler  No.  69. 

Test  No.  135. 
Manner  of  start  and  stop  and  kind  of  run,      ....          Ordinary. 

Duration, 10.1  hrs. 

Coal  consumed,  (  including  91  pounds  leather  scraps  taken  to 

be  equal  to  91  pounds  of  coal),        ....      2,972  Ibs. 

Percentage  of  ash, .        .        .16.4  per  cent. 

Water  evaporated, 23,396  Ibs. 

Coal  per  hour, 294  Ibs. 

Coal  per  hour  per  square  foot  of  grate,           .        .        .           10.9  Ibs. 

Water  per  hour, 2,314.1  Ibs. 

Water  per  hour  per  square  foot  of  water-heating  surface,      2.7  Ibs. 

Horse-power  developed, 73.9  H.  P. 

Boiler  pressure,          .........  84  Ibs. 

Temperature  of  feed-water, 150  cleg. 

Temperature   of  escaping  gases,      .                 .        .        .         428  deg. 

Draught  suction, 0.12  in. 

Water  per  pound  of  coal, 7.87  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .         .     8.66  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,    10.36  Ibs. 

NOTE. —When  the  water  was  carried  below  the  ordinary  level,  the  steam  was 
superheated  a  few  degrees.  Ordinarily  the  thermometer  failed  to  show  any  superheat. 

The  test  on  Boiler  No.  69  shows  the  performance  of  a  water 
tube  boiler,  using  one  of  the  small  grades  of  anthracite  coal. 
The  ratio  of  heating  surface  to  grate  surface  is  somewhat  small 
for  a  water  tube  boiler.  As  a  result,  the  temperature  of  the 
waste  gases  is  above  the  point  of  the  best  efficiency,  and  the 
evaporative  result,  which  is  10.36  pounds  of  water  from  and 
at  212  per  pound  of  combustible,  is  somewhat  unfavorable. 


230 


BOILEE    TESTS. 


Little  effect  seems  to  have  been  produced  by  the  steam  heat- 
ing surface,  so  far  as  it  could  be  observed  from  the  ther- 
mometer immersed  in  the  steam. 


Boiler  No.  7O. 


Kind  of  boiler,  .        . 
Number  used,      .        . 
Horse-power   (  basis  12  sq.  ft.  ), 
Kind  of  coal,      .        ..." 
Age,     .        .        .        .... 


Water  tube. 

One. 

One  hundred  and  thirty-six. 

Bituminous  Cambria. 

Eight  years. 


Boiler  No.   70  is  a  water   tube  boiler  having  the  general 
features  shown  in  the  cut  of  Boiler  No.  66. 


Dimensions  of  Boiler  No.  70. 

Number  of  tubes  4  inches  outside  diameter,  .        .•  .   >  .  80 

Length  of  tubes,       .        .        .        .      '  .   '"•'.        .    •  ;  .  18  ft. 

Diameter  of  drums  (two),     .        .        .        „        .  ,  „  30  in. 

Mean  length  of  drums,     .                 .      • ,        .        .  ..  7  ft.  6  in. 

Area  of  heating  surface,         ;i.        .        ...  .  .  .  1,638  sq.ft. 

Area  of  grate  surface,     .        .       *„        .        •••-..  .  .  36  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,         .  .  .  3-4  in. 

Ratio  of  heating  surface  to  grate  surface,      .  .     ...  -.  i.  45.5  to  1 

fie  suits  of  Tests.     Boiler  No.    70. 


Manner  of  start  and  stop  and  kind  of  run,       •  . 
Duration,    .        ..        »        .        .        .        •     ?  • 
Coal  consumed,  dry  (  including  wood  equivalent  ), 
Percentage  of  ash,     *        .        .        .        ...        . 

Water  evaporated,      .        .        .        .     •  .        . 

Coal  per  hour,    ...... 

Coal  per  hour  per  square  foot  of  grate,          .       •. 
Water  per  hour.      •   ;        .        .        .  ,    •     •  • 
Water  per  hour  per  square  foot  of  heating  surface, 
Horse-power  developed,     .        •        » 

Boiler  pressure, 62.4 

Temperature  of  feed-water,     .        .'   ' 883 

Temperature  of  escaping  gases,        ...        .        .        .         471 


Test  No.  136 
Ordinary. 
.  10.6  hrs. 

6,185  Ibs. 

.  10.5  per  cent. 


52,206 
608.9 
.  16.89 
4,946 
.    3 
166.3 


Draught  suction, 

Percentage  of  moisture  in  steam, 

Water  per  pound  of  coal,    ....... 

Water  per  pound  of  coal  from  and  at  212  degrees,   . 
Water  per  pound  of  combustible  from  and  at  212  degrees, 
NOTE.  —  The  coal  when  fired  contained  3.7  per  cent,  of  moisture. 


Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
H.  P. 
Ibs. 
deg. 
cleg, 
in. 

0.42  percent. 

8.44          Ibs. 

9.78          Ibs. 

10.93          Ibs. 


0.2 


BOILER  No.   71.  231 

The  test  on  Boiler  No.  70  shows  the  performance  of  a  water 
tube  boiler,  using  Cambria  bituminous  coal.  The  power 
developed  is  somewhat  more  than  its  nominal  capacity,  and  a 
hiijh  rate  of  combustion  prevails.  The  temperature  of  the 
escaping  gases  is  above  the  economical  limit,  and  the  evapora- 
tive result  is  correspondingly  low.  The  quantity  of  ash 
contained  in  the  coal,  viz.  10.5  per  cent.,  is  higher  than  is 
found  in  the  best  grades  of  bituminous  coal,  and  to  this 
indication  of  inferior  quality  of  fuel  may  be  attributed  in  some 
measure  the  low  degree  of  econonry  which  was  obtained. 

Boiler' No.  71. 

Kind  of  boiler, Water  tube. 

Number  used, Two. 

Horse-power  (  collective,  basis  12  sq.  ft.  ),    One  hundred  and  fifty-seven. 

Kind  of  coal, George's  Creek  Cumberland. 

Age,          .......        Four  years. 

Boiler  No.  71  is  a  water  tube  boiler,  having  the  general 
features  shown  in  the  cut  of  Boiler  No.  66.  It  embraces  two 
boilers  set  in  one  battery  of  brick  work. 

Dimensions  of   Boiler  No.  71. 
Number  of  tubes  4  inches  outside  diameter,  .        .        .        96 

Length  of  tubes,  16    ft. 

Diameter  of  drums  (two), 30  in. 

Length  of  drums, 16  ft.  6  in. 

Area  of  heating  surface,         .        .        .'.'..        .         .        .  1,886  sq.  ft. 

Area  of  grate  surface, 38.9  sq.  ft. 

Area  through  flue, 9.2  sq.  ft. 

Width  of  air  spaces  and  metal  bars  in  grates,   Air  5-8  in.,  metal  3-8  in. 

Ratio  of  heating  surface  to  grate  surface,     .         .        .        .      48.4  to  1 

Ratio  of  grate  surface  to  flue  area, 4.3  to  1 

Results  of  Test,  Boiler  No.  71. 

Test  No.  137 
Manner  of  start  and  s*op  and  kind  of  run,      .        .  .          Ordinary. 

Duration, 10  hrs. 

Coal  consumed,  dry  ( including  wood  equivalent ),          .      6,812  Ibs. 

Percentage  of  ash, .        .6.4  per  cent. 

Water  evaporated,     .        .        .        .        .        .        .        .59,113  Ibs. 

Coal  per  hour, 634.9  Ibs. 

Coal  per  hour  per  square  foot  of  grate, 16.3  Ibs. 

Water  per  hour, 5,510.6  Ibs. 

Water  per  hour  per  square  foot  of  heating  surface,       .        .2.9  Ibs. 


232  BOILER   TESTS. 

Horse-power  developed, 189.3  H.  P. 

Boiler  pressure, 72.9  Ibs. 

Temperature  of  feed-water, 66  deg. 

Temperature  of  escaping  gases,       .        .        .        .        .         523  deg. 

Draught  suction, 0.21  in- 

Percentage  of  moisture  in  steam, 0.4  per  cent. 

Water  per  pound  of  coal,          .......    8.68  Ibs. 

Water  per  pound  of  coal  from  and  at  212  degrees,          .        .  10.28  Ibs. 

Water  per  pound  of  combustible  from  and  at  212  degrees,       10.98  Ibs. 

The  test  on  Boiler  No.  71  shows  the  performance  of  a  water 
tube  boiler  using  Cumberland  bituminous  coal.  The  condi- 
tions under  which  the  tests  were  made  are  all  favorable  to 
good  economy  with  the  exception  of  one,  that  is,  the  tempera- 
ture of  the  escaping  gases.  This  is  so  far  above  the  economic 
point  that  it  fully  accounts  for  the  somewhat  low  evaporative 
.result  secured,  this  being  10.98  pounds  of  water  from  and  at 
.212  per  pound  of  combustible.  It  is  difficult  to  assign  a 
satisfactory  cause  for  the  high  temperature  of  the  waste  gases 
in  this  case.  It  is  evidently  due  to  inefficiency  of  heating 
surface,  but  the  difficulty  lies  in  determining  the  cause  of  the 
inefficiency.  It  is  known  that  the  interior  surfaces  of  the 
•boiler  were  clean ;  the  exterior  surfaces  were  as  clean  as  the 
'thorough  use  of  a  steam  jet  could  make  them.  Either  this 
method  of  removing  the  deposits  of  soot  from  the  exterior  of 
the  pipes  did  not  accomplish  its  purpose,  or  there  is  some 
fault  in  the  arrangement  of  the  heating  surface,  whereby  it 
fails  to  properly  absorb  the  heat. 

Preparatory  to  the  test  on  this  boiler  the  cracks  in  the  brick 
work,  and; all  the  crevices  around  the  doors,  with  which  the 
'boiler  is  .provided  for  purposes  of  cleaning,  were  filled  with 
fire  clay.  The  effect  of  reducing  by  this  means  the  quantity 
of  air  which  was  drawn  in  was  revealed  by  means  of  the 
draught  gauge.  With  no  fire  in  the  furnace,  and  the  fire  and 
ash  doors  closed,  a  draught  of  0.31  of  an  inch  in  the  main 
flue,  with  wide  open  damper,  produced  a  draught  of  0.25  of 
an  inch  between  the  damper  and  the  boiler,  before  the  open- 
ings were  closed,  and  the  full  draught  of  0.31  of  an  inch  after 
they  were  closed.  When  the  damper  was  in  a  partly  closed 


BOILER  No.  71.  233 

position,  the  draught  in  the  main  flue  remaining  the  same,  the 
amount  realized  was  0.09  of  an  inch  before  stopping  up  the 
openings,  and  0.20  of  an  inch  after  stopping  them  up.  The 
crevices  were  not  fully  closed,  else  the  full  draught  would 
have  been  realized  when  the  damper  was  partially  open. 
Repeated  tests,  made  beforehand,  with  open  crevices,  showed 
a  lower  economic  result  than  that  given  here,  and  this  proves 
that  the  leakage  of  too  much  air  into  a  furnace  produces  an 
unfavorable  effect  upon  the  economy. 


234 


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SUMMARY. 


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BOILER    TESTS. 


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APPENDIX. 


APPENDIX. 


A   COAL  CALORIMETER. 

EXPERIMENTS    ON    THE    HEATING   POWER    OF   VARIOUS    COALS. 

These  experiments  were  made  to  determine  the  heating 
power  of  several  different  kinds  of  coal,  used  on  evaporative 
tests  of  various  boilers. 

They  have  an  important  scientific  application  to  the  work  of 
making  boiler  tests,  and  an  even  more  important  commercial 
application  to  the  interests  of  those  who  use  coal  in  large 
quantities.  An  intending  purchaser  may,  by  employing  the 
instrument  under  notice,  determine  beforehand  the  exact 
value  of  the  different  coals  offered  by  dealers,  and  may  at  any 
subsequent  time  determine  whether  he  has  received  coal  of  the 
quality  contracted  for. 

The  apparatus  used  for  the  experiments  consists  of  a  calori- 
meter, in  which  a  small  quantity  of  the  coal  is  burned,  and  the 
heat  derived  therefrom  is  imparted  to  the  water  which  the 
instrument  contains.  The  combustion  is  effected  in  an 
atmosphere  of  oxygen  beneath  the  surface  of  the  water,  and 
the  products  of  combustion  are  made  to  give  up  their  heat  to 
the  water  by  mingling  with  the  liquid  itself  in  the  act  of  rising 
to  the  surface  and  escaping.  The  coal  used  is  that  obtained 
by  carefully  sampling  the  coal  employed  on  the  evaporative 
test,  and  a  representative  portion  of  the  sample  is  selected  and 
finely  pulverized.  One  gramme  in  weight  of  the  pulverized 
coal  is  measured  out  and  placed  in  a  small  platinum  crucible. 
This  is  set  in  an  inverted  chamber,  having  a  perforated  base, 
which  is  immersed  in  the  water  of  the  calorimeter.  The 
chamber  is  supplied  with  oxygen  gas  through  a  pipe  leading 

240 


250  BOILER   TESTS. 

from  a  tank  containing  oxygen,  placed  close  by,  and  the  coal 
is  ignited.  The  products  of  combustion  escape  downward 
through  the  perforated  bottom  of  the  chamber,  and  bubble  up 
through  the  water,  finally  being  discharged  at  the  surface  of 
the  liquid  into  the  atmosphere.  The  quantity  of  water  used  is 
2  kilograms,  or  2000  times  the  weight  of  coal.  The  tempera- 
ture of  the  water  is  observed  before  the  coal  is  lighted,  and 
again  at  the  end  of  the  process  of  combustion,  and  the  rise  of 
temperature  furnishes  the  principal  element  in  the  required 
data.  The  material  of  which  the  instrument  is  composed 
possesses  a  heat  capacity  equivalent  to  that  of  an  additional 
weight  of  114  grammes  of  water.  The  coefficient  of  the 
apparatus  for  one  degree  rise  of  temperature  is  thus  2114.  In 
other  words,  the  heating  power  or  total  heat  of  combustion  of 
a  unit  of  weight  of  the  coal  is  2114  units  of  heat  for  each 
degree  rise  of  temperature.  If,  for  example,  the  water  is 
heated  6  degrees  Fahrenheit,  the  total  heat  of  combustion  of  1 
pound  of  coal  is  2114x6  =  12,684  B.  T.  U. 

The  results  of  the  calorimeter  tests  are  summarized  in  the 
following  Table,  and  these  are  given  in  connection  with  the 
principal  results  of  the  evaporative  tests  of  the  boilers. 

Test  A,  which  gave  a  total  heat  of  13,529  thermal  units, 
was  made  on  a  Cumberland  bituminous  coal,  which  was  used 
in  a  cast-iron  sectional  boiler.  The  heating  surface  in  the 
boiler  amounted  to  2815  square  feet  and  the  ratio  of  heating 
surface  to  grate  surface  was  53  to  1.  The  firing  was  done  in 
a  very  careful  manner  by  a  special  fireman.  Although  the 
temperature  of  the  escaping  gases  was  460  degrees,  which  is 
excessive,  the  evaporative  result  was  10.8  pounds,  uncorrected 
for  moisture  which  was  present  in  the  steam  to  the  extent  of 
0.5  per  cent.  This  performance  is  not  so  high  as  that 
obtained  on  some  of  the  boilers  given  in  Part  II.,  with  the 
same  kind  of  coal.  The  evaporation  taken  to  represent  a 
fair  performance  under  favorable  conditions,  given  on  page 
45  of  Part  I.,  is  11.04  pounds  of  water  from  aiid  at  212 
degrees  per  pound  of  coal. 


APPENDIX. 


251 


252  BOILER   TESTS. 

Tests  B  and  C  were  made  on  two  coals  used  on  evaporative 
tests  of  a  plant  of  five  vertical  tubular  tire  box  boilers  encased 
in  brick  work.  One  of  the  coals  was  a  Pocahontas  bitumi- 
nous, and  the  other  a  George's  Creek  Cumberland  bituminous. 
The  collective  total  heating  surface  amounted  to  10,940  square 
feet.  The  ratio  of  this  total  surface  to  grate  surface  was  54.5 
to  1,  and  about  70  per  cent,  of  this  was  water  heating 
surface,  and  30  per  cent,  steam  heating  surface.  The 
Pocahontas  coal  gave  a  total  heat  of  14,375  thermal  units, 
and  the  Cumberland  coal,  13,213,  while  the  two  results  of  the 
evaporative  tests,  including  allowance  for  the  added  heat  due 
to  superheating,  which  was  31  degrees  in  the  first  test,  and  47 
degrees  in  the  second,  were  respectively  9.60  pounds  and  8.93 
pounds.  The  heat  given  by  the  Cumberland  coal  is  8  per 
cent,  less  than  that  given  by  the  Pocahontas  coal,  and  the 
difference  between  the  two  evaporative  results  is  7  per  cent. 
The  calorimeter  in  these  cases  shows  that  the  difference  in  the 
results  of  the  tests  is  well  accounted  for  by  the  difference  in 
the  quality  of  the  fuel. 

Tests  D,  E  and  F  were  made  with  three  samples  of  George's 
Creek  Cumberland  bituminous  coal,  used  on  a  series  of  loco- 
motive trials.  These  coals  were  all  obtained  from  the  same 
dealer,  and  they  were  said  to  be  of  the  same  kind,  but  they 
were  delivered  in  three  different  cities,  and  it  may  be  pre- 
sumed that  they  were  taken  from  three  different  lots.  Between 
the  highest  and  lowest  results  of  these  tests  there  is  a  differ- 
ence of  1078  thermal  units,  or  about  8  per  cent,  of  the  lowest 
quantity,  and  this  range  indicates  the  variation  in  quality 
which  may  occur  with  different  samples  of  merchantable  coal, 
supposed  to  be  of  the  same  kind. 

Test  G  was  made  with  a  George's  Creek  Cumberland  coal, 
used  on  an  evaporative  test  of  a  water  tube  boiler.  The  heat- 
ing surface  in  the  boiler  amounted  to  2765  square  feet,  and  the 
ratio  of  heating  surface  to  grate  surface  was  46.5  to  1.  The 
heating  power  of  the  coal  shown  by  the  calorimeter,  which  was 
13,973  thermal  units,  is  higher  than  that  given  by  any  other 
Cumberland  coal  on  the  list;  but  the  evaporative  result, 


APPENDIX.  253 

which  was  10.06  pounds,  is  below  that  given  by  some  of  the 
other  boilers  using  the  same  kind  of  coal.  It  is  evident  that 
the  low  result  cannot  be  attributed  to  an  inferior  quality  of 
fuel. 

Test  H  was  made  on  a  Clearfield  bituminous  coal  used  on  a 
test  of  a  plant  of  two  double-deck  horizontal  return  tubular 
boilers.  The  area  of  heating  surface  amounted  to  3860  square 
feet,  the  ratio  of  which  to  the  grate  surface  was  67  to  1.  The 
heating  power  of  the  coal  is  here  13,043  thermal  units.  This 
is  930  thermal  units,  or  6.6  per  cent,  below  the  result  of  test 
G  made  on  Cumberland  coal.  This  evidence  of  inferior 
quality  furnishes  a  partial,  if  not  a  full,  explanation  of  the 
comparatively  low  degree  of  economy  shown  by  the  evapor- 
ative test. 

Test  I  was  made  on  a  Frontenac  slack  coal,  mined  in  South- 
ern Kansas,  which  was  used  on  a  test  of  two  72  inch  horizon- 
tal return  tubular  boilers.  The  area  of  the  heating  surface 
was  2684  square  feet,  and  the  ratio  of  heating  surface  to  grate 
surface  44.4  to  1.  No  evaporative  test  was  made  in  this  case, 
but  from  the  results  of  a  test  of  an  engine,  to  which  the 
boilers  were  furnishing  steam,  the  evaporation  appeared  to  be 
6  pounds  of  water  from  and  at  212  degrees  per  pound  of  coal. 
The  boilers  were  poorly  fired,  and  this  accounts  in  a  measure 
for  the  low  economy  indicated ;  but  it  is  evident  that  this 
result  is  chiefly  due  to  the  inferior  quality  of  the  fuel.  The 
calorimeter  test  gave  10,506  thermal  units,  which  is  only  75 
per  cent,  of  the  result  given  for  the  best  Cumberland  coal  in 
the  Table. 

Test  J  was  made  on  a  Cape  Breton  bituminous  coal,  from 
the  Caledonia  mine,  which  was  used  on  a  test  of  two  66  inch 
horizontal  return  tubular  boilers.  The  heating  surface  was 
1931  square  feet,  the  ratio  of  which  to  grate  surface  was  29.5 
to  1.  A  comparatively  low  evaporative  result  was  obtained, 
being  8.22  pounds  of  water,  and  this  was  caused  in  some 
degree  by  poor  firing.  The  low  heating  power  shown  by  the 
calorimeter  appears  however  to  be  the  main  cause  of  the 
inferior  economy.  The  heat  of  combustion  was  12,515 


254  BOILER    TESTS. 

thermal  units,  or  90  per  cent,  of  the  heat  shown  with  the  best 
Cumberland  coal  on  the  list. 

Test  K  was  made  with  a  Honeybrook  anthracite  coal  of  the 
Chestnut  No.  2  size,  which  was  used  on  a  test  of  a  plant  of 

five  horizontal  return  tubular  boilers.     The  collective  heating 

& 

surface  amounted  to  6772  square  feet,  and  the  proportion  of 
heating  surface  to  grate  surface  was  49.3  to  1.  The  amount 
of  heat  shown  by  the  calorimeter  is  11,733  thermal  units,  and 
this  is  much  below  the  result  obtained  from  the  Cumberland 
bituminous  coals.  The  evaporative  result,  which  was  9.18 
pounds,  is  likewise  comparatively  low.  Comparing  these 
figures  with  those  obtained  on  test  A,  the  total  heat  of  com- 
bustion of  the  anthracite  coal  is  13  per  cent,  less  than  that 
with  the  Cumberland  coal,  and  the  evaporative  result  is  15 
per  cent.  less. 

Test  L  was  also  made  with  an  anthracite  Chestnut  No.  2 
<coal.  In  this  case  the  boiler  was  of  the  plain  cylinder  type, 
having  a  heating  surface  of  394  square  feet,  and  a  ratio  of 
heating  surface  to  grate  surface  of  10.9  to  1.  The  tempera- 
ture of  the  escaping  gases  was  above  the  melting  point  of  zinc. 
This  boiler  is  the  one  designated  as  No.  49  in  Part  II.,  and 
the  test  referred  to  is  the  one  numbered  99.  The  heating 
power  of  the  coal  on  this  test  is  slightly  below  that  of  test  K, 
but  this  does  not  account  in  any  degree  for  the  exceedingly  low 
jevaporative  result  obtained,  which  was  5.75  pounds  of  water. 
The  low  result  is  almost  wholly  due  to  the  deficiency  of  heat- 
ing surface. 

Test  M  was  made  with  a  George's  Creek  Cumberland  coal, 
used  on  a  test  of  a  Galloway  boiler,  in  which  the  heating 
surface  amounted  to  938  square  feet,  and  the  ratio  of  heating 
surface  to  grate  surface  was  25.9  to  1.  This  is  the  boiler 
which  is  designated  in  Part  II.,  as  No.  50,  and  the  evapora- 
tive test  given  is  the  one  referred  to  in  the  comments  on  the 
results  of  the  tests  in  connection  with  that  boiler.  The 
evidence  of  the  calorimeter  test,  which  gave  a  total  heat  of 
13,867  thermal  units,  is  that  the  fuel  was  of  superior  quality 
to  that,  for  example,  of  test  A.  But  this  did  not  lead  to  a 


APPENDIX.  255 

superior  evaporative  result,  there  being  on  the  contrary,  a  loss 
referred  to  that  test  of  nearly  5  per  cent.  The  difference  in 
the  evaporative  results  must  be  explained  by  the  difference  in 
the  efficiency  of  the  two  types  of  boilers,  and  the  data  given  in 
connection  with  the  boiler  tests  show  wherein  this  is  brought 
about. 

A  UNIVERSAL   STEAM   CALORIMETER. 

This  instrument  was  devised  by  the  author  in  1889,  and  it 
has  since  that  time  been  used  where  formerly  the  Superheating 
Calorimeter,  referred  to  in  Part  I.,  was  employed.  It  is 
fully  described  in  the  Transactions  of  the  American  Society  of 
Mechanical  Engineers,  Volume  11,  and  the  following  account 
is  taken  from  that  publication.  It  is  of  simpler  form  than  the 
Superheating  Calorimeter,  and  it  has  a  wilder  application,  but 
it  is  no  less  accurate.  The  current  of  steam  to  be  tested  is 
first  passed  through  a  chamber  in  which  the  free  moisture  is 
deposited  and  measured,  and  subsequently  it  is  carried  through 
an  orifice  and  discharged  to  the  atmosphere,  by  means  of  which 
the  partially  dried  steam  is  wiredrawn  and  superheated,  and 
its  exact  final  condition  determined.  The  apparatus  is  shown 
in  the  following  cut. 


256 


BOILER    TESTS. 


The  principal  parts  consist  of  the  chamber  A,  or  "  drip- 
box,"  and  the  wiredrawing  apparatus  or  "  heat-gauge,"  con- 
sisting of  the  orifice  /,  and  the  two  thermometers  M  and  JV. 
The  instrument  is  connected  to  the  main  steam-pipe  G,  which 
carries  the  steam  to  be  tested,  by  means  of  the  perforated  pipe 
F,  and  this  pipe  extends  across  the  full  diameter,  in  order  to 
obtain  a  sample  of  the  steam  tested.  The  orifice  /opens  into 
a  pipe  which  is  in  free  communication  with  the  atmosphere. 
By  the  use  of  the  orifice  a  continuous  current  of  steam  is  made 
to  pass  through  the  whole  apparatus,  and  the  current  has  a 
constant  rate  so  long  as  the  pressure  is  constant.  In  the  form 
thus  far  made,  the  supply  pipe  F,  and  the  fittings,  up  to  the 
drip-box  are  the  ordinary  size  of  one-half  inch  steam  pipe. 
The  drip- box  is  11  in.  inside  diameter  and  10  inches  long, 
and  the  drain-pipe  D  is  one  fourth  inch  pipe.  The  pipe  leav- 


APPENDIX.  257 

ing  the  drip-box  is  also  one-half  inch,  and  the  remaining  pipes 
and  fittings  are  of  the  three-fourths  inch  size.  The  parts 
marked  j$,  which  enclose  a  plate  in  which  the  orifice  is  placed, 
are  a  pair  of  union  flanges,  and  inserted  between  these  flanges 
and  under  the  bolt-heads  are  pieces  of  non-conducting 
material  which  prevent  the  direct  transfer  of  heat  through  the 
metal  walls  of  the  high-pressure,  pipe  above  the  orifice  to  the 
walls  of  the  low-pressure  pipe  below  it.  The  thermometer 
M  rests  in  an  oil-cup,  A%  as  shown,  and  the  thermometer  JVis 
arranged  in  a  like  manner. 

The  use  of  the  non-conducting  material  shown  at  the  points 
eT",  might  seem  to  some  unnecessary,  and  it  may  be  explained 
that  in  some  early  experiments  with  the  superheating  calori- 
meter it  was  found  absolutely  necessary  to  cut  off  all  solid 
metallic  connection  between  the  jacket  and  the  interior  heating 
pipe,  else  there  would  be  a  transfer  of  heat  from  one  to  the 
other,  which  would  make  the  indications  of  the  thermometers 
erroneous.  The  same  principle  applies  here,  and  justifies  the 
arrangement  which  has  been  adopted. 

The  orifice  /  is  made  about  one-eight  of  an  inch  in  diameter 
for  pressures  in  the  neighborhood  of  80  pounds,  and  at  80 
pounds  pressure  it  discharges  about  60  pounds  weight  of 
steam  per  hour. 

The  amount  of  moisture  which  the  heat  gauge  alone  will 
measure  varies  somewhat  according  to  the  pressure.  If  the 
pressure  is  eighty  pounds,  it  will  measure  between  3  per  cent, 
and  4 -per  cent.  It  is  unnecessary  to  use  the  drip-box  unless 
the  quantity  of  moisture  is  in  excess  of,  say,  3  per  cent.  The 
unions  P  and  Q  are  therefore  made  interchangeable.  When  a 
test  is  to  be  made,  the  heat-guage  is  first  applied  directly  to 
the  union  Q  and  a  preliminary  trial  made,  to  see  what  the 
general  condition  of  the  steam  is.  Whenever  the  moisture 
exceeds  3  per  cent.,  or  the  limiting  quantity  at  the  existing 
pressure,  the  thermometer  JV  shows  a  temperature  of  about 
213  degrees,  and  drops  of  water  will  generally  be  seen  escap- 
ing from  the  open  discharge-pipe.  If  the  quantity  of  moisture 
is  not  beyond  the  range  of  the  wire-drawing  instrument,  the 


258  BOILER    TESTS. 

temperature  shown  by  thermometer  .AT  will  be  in  excess  of  213 
degrees. 

It  is  generally  advisable  to  bring  the  complete  apparatus 
into  use,  if  the  thermometer  _2V  shows  less  than  220  degrees. 
It  is  usually  found,  when  the  steam  is  wet  enough  to  show 
this  latter  temperature,  that  the  quantity  of  moisture  varies, 
and  thermometer  ^fluctuates  over  a  considerable  range,  and 
at  times  it  will  drop  to  its  limit  of  213  degrees.  Whenever, 
therefore,  thermometer  JV shows  a  temperature  of  213  degrees, 
either  continuously  or  periodically,  it  is  necessary  to  bring  the 
drip-box  into  use. 

In  using  the  complete  apparatus,  the  condensed  water  from 
the  drip-box  is  drawn  off",  by  means  of  the  valve  Z>,  into  a 
bucket  resting  on  scales,  and  the  quantity  drawn  off  is  regu- 
lated so  as  to  keep  the  water  level,  as  shown  in  the  glass  (7, 
at  a  constant  point.  When  the  drip-box  is  used  in  this  way, 
the  author  has  found  that  almost  the  whole  quantity  of 
moisture  in  a  sample  will  be  deposited  here,  and  very  little 
moisture  will  be  left  to  pass  over  into  the  heat-gauge. 
Indeed,  the  experiments  show  that  the  drip-box  alone,  with  a 
suitable  orifice  or  valve  provided  at  the  top,  so  as  to  obtain  a 
proper  circulation  through  it,  would  form  a  very  satisfactory 
instrument  for  determining  the  quantity  of  moisture,  in  any 
case  where  the  steam  contained  much  of  it. 

When  the  quantity  of  moisture  drawn  off  from  the  drain- 
valve  D  has  been  determined  for  a  given  time,  the  percentage 
of  moisture  which  this  represents  must  be  found  by  comparing 
it  with  the  total  amount  of  steam  passing  through  the 
apparatus.  The  total  may  be  determined  either  by  computa- 
tion or  by  trial.  The  computation  may  be  made  by  finding 
the  exact  area  of  the  orifice,  and  computing  the  quantity  which 
passes  through  by  means  of  the  formula, 

^ Pressure  above  zero  x  area, 

V=  ~1Q~ 

which  gives  the  number  of  pounds  discharged  through  the 
orifice  per  second.  The  pressure  to  be  used  is  that  corres- 
ponding to  the  temperature  shown  by  thermometer  M.  The 


APPENDIX.  259 

quantity,  as  thus  found,  is  accurate  enough  for  rough  com- 
parisons. The  exact  quantity  can  be  determined  by  conduct- 
ing the  steam  discharged  from  the  open  end  of  the  apparatus 
into  a  tub  of  water  placed  on  scales  —  or,  what  is  a  better 
way,  into  a  coil  of  lead-pipe,  or  iron-pipe,  surrounded  by 
flowing  water,  in  the  manner  of  a  surface  condenser,  and 
weighing  the  condensed  water  drawn  off  in  a  given  time. 

A  certain  amount  of  moisture  is  produced  by  radiation  from 
the  apparatus  itself,  even  though  all  the  parts  are  well  covered, 
as  it  is  quite  necessary  that  they  should  be,  with  hair  felting. 
The  readings  of  the  instrument  on  the  test  must  therefore  be 

O 

corrected  for  the  loss  thus  occasioned.  It  has  been  the 
practice  of  the  author  to  make  these  corrections  by  observing 
the  indications  when  the  apparatus  is  supplied  with  steam 
from  the  pipe  6r,  at  a  time  when  the  pressure  is  steady  and 
the  pipe  contains  nothing  but  dead  steam,  there  being  no 
current.  This  condition  of  things  can  generally  be  obtained 
in  a  factory  at  noon-time,  when  the  engine  is  stopped,  or  at 
night,  after  the  close  of  the  day's  work.  It  may  fairly  be 
presumed  tha ';  the  apparatus  is  then  supplied  with  dry  steam 
and  whatever  moisture  collects  in  the  drip-box  A,  and  what- 
ever difference  is  shown  by  thermometers  M  and  N,  is  due 
simply  to  the  loss  of  heat  from  radiation.  When  the  loss 
from  radiation  has  been  thus  obtained,  the  quantity  represent- 
ing that  due  to  the  drip-box  is  simply  subtracted  from  the 
weight  of  water  drawn  off  during  the  same  length  of  time  on 
the  main  test.  The  way  in  which  the  correction  is  applied  to 
the  readings  of  thermometers  M  and  N  is  to  take  the  reading 
of  thermometer  N  on.  the  radiation  test  when  thermometer  M 
indicates  an  average,  and  use  this  reading  as  a  starting-point. 
The  indication  of  thermometer  JV"  on  the  main  test  is  then 
simply  subtracted  from  this  normal  reading.  For  example, 
suppose  the  average  reading  of  the  upper  thermometer  (  M) 
during  the  main  test  is  312  degrees  ;  suppose  the  lower  ther- 
mometer (  N)  indicates  an  average  of  260  degrees  on  the 
main  test,  and  on  the  radiation  trial  suppose  it  indicates  267 
degrees  when  thermometer  M  shows  312  degrees;  the 


260  BOILER    TESTS. 

process  would  be  simply  to  subtract  260  from  2(57,  and  this 
would  give  seven  degrees  as  the  cooling  effect  produced 
by  the  moist  steam  discharged  on  the  main  test. 

In  order  to  compute  the  amount  of  moisture  from  the  loss 
of  temperature  shown  by  the  heat-gauge,  the  number  of 
degrees  of  cooling  of  the  lower  thermometer  (  JV)  is  divided 
by  a  certain  coefficient,  representing  the  number  of  degrees  of 
cooling  due  to  1  per  cent,  of  moisture.  This  coefficient 
depends  upon  the  specific  heat  of  superheated  steam,  which, 
according  to  Regnault's  experiments,  is  0.48.  In  other  words, 
the  heat  represented  by  1  degree  of  superheating  is  0.48 
of  a  thermal  unit.  The  author's  experiments  show  that  this 
quantity  cannot  be  applied  exactly  to  the  form  of  instrument 
under  consideration.  The  quantity  to  be  used  varies  some- 
what according  to  the  degree  of  moisture.  For  an  instrument 
working  under  a  temperature  of  314  degrees,  by  the  upper 
thermometer,  and  with  a  cooling  by  the  lower  thermometer 
from  268  degrees  to  241  degrees,  the  quantity  was  found  to  be 
about  0.42.  When  the  cooling,  however,  was  from  266 
degrees  to  225  degrees,  the  quantity  to  be  used  was  found  to 
be  about  0.51.  The  experiments  have  not  as  yet  covered  a 
sufficient  range  to  determine  the  exact  law  which  can  be 
applied  to  every  case,  but  it  seems  probable  that  the  specific 
heat  is  more,  or  less  constant  until  the  temperature  by  the 
lower  thermometer  approaches  the  point  of  saturation  for  the 
low-pressure  steam,  while  beyond  this  point  the  specific  heat 
rapidly  increases.  For  the  present,  it  is  assumed  that  the 
quantity  0.42  is  the  proper  one  to  apply  whenever  the  tempera- 
ture by  the  lower  thermometer  is  above  235  degrees,  and  that 
in  cases  where  the  temperature  is  below  235  degrees,  the  quan- 
tity to  be  used  is  an  increasing  one,  reaching  perhaps  to  0.55 
when  the  temperature  drops  to  220  degrees. 

One  per  cent,  of  moisture,  now,  represents  the  quantity  of 
heat  determined  by  multiplying  the  latent  heat  of  one  pound 
of  steam,  having  a  pressure  corresponding  to  the  indication  of 
thermometer  3f,  by  0.01,  and  this  product  is  to  be  divided  by 
0.42  ( provided  the  lower  temperature  is  not  below  235 


APPENDIX. 


261 


degrees  ) ,  in  order  to  express  it  in  terms  of  degrees  of  super- 
heat. For  example :  When  thermometer  M  shows  312 
degrees,  the  latent  heat  is  894  thermal  units,  and  1  per  cent, 
of  this  is  8.94;  dividing  by  0.42,  the  number  of  degrees  of 
superheat  corresponding  to  1  per  cent,  of  moisture  is  found  to 
be  21.3.  For  several  other  temperatures,  which  cover  the 
ordinary  range  that  would  commonly  be  used,  the  necessary 
coefficient  is  given  in  the  following  table  : 


Temperature 

by 

Coefficient. 

Temperature 

*>y 

Coefficient. 

Thermometer  M. 

Thermometer  M. 

270 

22  0 

320 

21.1 

280 

21  8 

330 

21.0 

290 

21.7 

340 

20.8 

300 

21.5 

350 

20  fi 

310 

21.3 

360 

20.5 

The  utility  of  the  instrument,  and  the  general  manner  in 
which  it  operates  in  practice,  may  best  be  shown  by  reference 
to  the  various  tables  which  are  appended,  giving  the  results  of 
a  number  of  tests  on  different  boilers,  made  by  the  author. 

TEST  N. 

The  first  test  was  made  when  using  simply  the  wire-drawing 
part  of  the  instrument,  or  "  heat- gauge."  Only  one  ther- 
mometer was  applied  —  that  is,  the  lower  thermometer  —  and 
the  temperature  of  the  steam  above  the  orifice  is  only  to  be 
learned  by  the  indications  of  the  pressure-gauge  attached  to 
the  boiler.  The  boiler  was  one  which  gave  steam  of  varying 
degrees  of  dry  ness,  and  it  was  admirably  adapted  for  a  test  of 
this  kind.  It  consisted  of  two  shells,  the  lower  one  of  which 
was  nearly  filled  with  tubes,  and  the  upper  one  served  the  pur- 
pose of  a  drum.  The  connection  between  the  two  shells  was 
by  a  single  neck  at  the  front  end.  Two  steam-pipes  carried 
away  the  supply  of  steam ,  one  being  attached  at  the  front  end 
of  the  drum,  directly  over  the  connecting  neck,  and  the  other 
being  attached  to  the  rear  end.  The  smoke  and  products  of 


262  BOILEE  TESTS. 

combustion,  on  leaving  the  tubes,  passed  over  the  exterior 
surface  of  the  drum  on  their  way  to  the  chimney,  and  the 
drum  thus  furnished  a  certain  amount  of  steam-heating  sur- 
face. The  calorimeter  was  attached  first  to  one  of  these  pipes 
and  then  to  the  other.  The  boilers  at  this  place  were  two  in 
number,  and  the  calorimeter  was  attached  to  only  one.  When 
the  instrument  was  applied  to  the  front  pipe,  the  quality  of 
the  steam  indicated  was  quite  variable,  but  when  it  was 
attached  to  the  rear  pipe,  the  quality  became  nearly  constant, 
and  the  indications  pointed  to  a  small  amount  of  superheating. 
The  indications  of  the  instrument  on  the  front  pipe  revealed 
an  exceedingly  interesting  state  of  affairs.  The  quality  of  the 
steam  fluctuated  periodically  over  a  considerable  range,  vary- 
ing from  a  condition  of  extreme  wetness  to  a  nearly  dry  con- 
dition. When  the  indications  pointed  to  the  largest  amount 
of  moisture,  the  thermometer  showed  about  213  degrees,  and 
drops  of  water  issued  with  the  steam  at  the  point  of  discharge. 
The  periodical  fluctuations  were  surprising,  until  a  careful 
observation  of  the  times  when  they  occurred  showed  that  the 
wet  steam  was  produced  according  to  the  rate  of  production 
of  steam  in  the  boiler  to  which  the  calorimeter  was  attached. 
The  firing  of  the  two  boilers  was  done  alternately,  and  when 
the  boiler  to  which  the  calorimeter  was  attached  was  fired, 
there  was  a  cessation  in  the  generation  of  steam  in  this  boiler, 
and  the  other  boiler  in  which  the  fire  was  active  was  drawn 
upon  to  make  up  the  deficiency.  At  this  time  the  thermome- 
ter in  the  calorimeter  boiler  always  showed  increasing  indica- 
tions. Whenever,  on  the  contrary,  the  other  boiler  was  fired, 
and  at  times  when  the  fresh  fires  in  the  calorimeter  boiler  had 
become  active  again,  the  indications  of  the  thermometer  would 
rapidly  fall.  At  such  times  the  auxiliary  boiler  became  for 
the  moment  inoperative,  and  the  calorimeter  boiler  was  called 
upon  to  furnish  the  greater  part  of  the  steam.  The  lower 
shell  of  the  boiler  being  nearly  filled  with  tubes,  and  the  gen- 
erating surface  in  this  shell  being  very  small,  there  was  an 
active  tendency  for  this  shell  to  carry  up  into  the  drum  a  mix- 
ture of  water  and  steam,  and  this  would  easily  find  its  way 


APPENDIX. 


263 


into  the  front  pipe,  directly  above,  whenever  the  boiler  was 
doing  much  work.  The  alternate  heating  and  cooling,  due  to 
the  periodical  firing,  produced  alternately  very  wet  and  nearly 
dry  steam  in  the  front  part  of  the  drum,  and,  as  a  consequence, 
it  produced  a  varying  degree  of  moisture  in  the  steam  which 
passed  through  the  front  pipe,  as  noted. 


Dimensions  and  Other  Data    regarding  Boiler  used  on  Test  N. 


1. 
2. 
8. 

4. 
5. 

0. 
7. 
8. 
9. 

10. 
11. 
12. 
13. 
14. 
15. 

10. 
17. 

18. 


Diameter  of  main  shell,          .         .        .         .         . 

Length  of  main  shell  and  length  of  tubes, 

Number  of  tubes  4  inches  outside  diameter, 

Size  of  grate,          .        .        .         .  ••     .        .        . 

Area  of  grate  surface,  .         .        .-  , 

Area  of  water-heating  surface,    .        . 

Area  of  steam-heating  surface, 

Area  of  total  heating  surface,       ...         .         . 

Collective  area  through  tubes,        .         .        . 

Ratio  of  total  heating  surface  to  grate  surface,  . 

Ratio  of  grate  surface  to  tube  area,     .... 

Kind  of  coal  used,          ...        .        . 

Percentage  of  ashes,      .         .        .        .        .    „   .        . 

Coal  burned  per  hour  per  square  foot  of  grate,  . 

Water  evaporated  per  square  foot  of  heating  surface 

per  hour,  .         .        .         .      '  ,      '  .     f>  . •  '     .' 

Average  temperature  of  flue  gases,       .         .  •  v- 

Average  draught  suction,       ...... 

Water  evaporated  per  pound  of  combustible  from  and 

at  212  degrees,  unconnected  for  moisture,       .        . 


.  32 
.934 
.107 
1,041 


54  in. 

17  ft. 

.  45 

4x8  ft. 

sq.  ft. 

sq.  ft. 

sq.  ft. 

sq.  ft. 


.     3.4  sq.  ft. 
.    32.5  to  1 
.      9.3  to  1 
Schuylkill  pea. 
.    17. 8  per  ct. 
.    11.5  Ibs. 


3.1  Ibs. 

420      deg. 

0.24  in. 


.    11.07  Ibs. 


TABLE  No.  1. 

Double-deck    Horizontal   Return    Tubular   Boiler,    Calorimeter     attached  to 

Front  Steam-pipe. 


Tempera- 

Condition of 

TIME  OF 

FIRING. 

ture  shown 

Steam  at 

Time. 

Boiler 
Gauge. 

by  Lower 
Thermome- 
ter of  Calori- 
meter. 

outlet  of  Cal- 
orimeter  as 
it   appeared 
to  the  eye. 

Position  of 
Damper. 

Auxiliary 
Boiler. 

Boiler  to 
which  Cal- 
orimeter 
was  ap- 
plied. 

10.00 

_ 

236 

Dry 

Wide  open 

10.00 

_ 

10.01 

— 

226 

Wet* 

_ 

— 

10.02 

- 

242 

Dry 

_ 

10.024 

10.03 

_ 

256 

•« 

_ 

_ 

10.04 

_ 

264 

ci 

_ 

_ 

10.05 

_ 

269 

it 

_ 

_ 

10.06 

- 

271.5 

a 

- 

- 

*  By  the  term  "  wet "  is  meant  that  drops  of  water  emerged  from  the  outlet  of  the 
calorimeter. 


264 


BOILER    TESTS. 


TABLE  NO.  In.  — Continued. 


Tempera- 

Condition of 

TIME  OF  FIRING. 

Time. 

Boiler 
Gauge. 

ture  shown 
by  Lower 
Thermome- 
ter of  Calo- 
rimeter. 

Steam  at  out- 
let of  Calori- 
meter as  it 
appeared  to 
the  eye. 

Position  of 
Damper 

Auxiliary 
Boiler. 

Boiler  to 
which    Calo- 
rimeter was 
applied. 

10.07 

- 

273.5 

« 

i  open. 

- 

_ 

10.08 

— 

272 

" 

" 

_ 

_ 

10  09 

_ 

265.5 

" 

" 

_ 

_ 

10.10 

_ 

264.5 

" 

" 

_ 

_ 

10.11 

_ 

230 

" 

44 

10.  iu 

_ 

10.12 

_ 

218 

Wet 

Wide  open 

_ 

_ 

10.13 

- 

222 

Dry 

" 

- 

- 

10.14 

— 

241 

" 

(4 

_ 

_ 

10.15 

- 

256 

" 

§   open 

_ 

10.15 

10.16 

_ 

268 

(4 

ti 

_ 

_ 

10.20 

88 

258 

M 

\   open 

- 

_ 

10.21 

_ 

246 

1  1 

" 

_ 

_ 

10.22 

_ 

226 

it 

" 

_ 

_ 

10.23 

- 

220.5 

Wet 

I  open 

10.221 

_ 

10.24 

- 

215.5 

" 

Wide  open 

_ 

_ 

10.25 

_ 

230 

" 

" 

_ 

_ 

10.  2G 

- 

246.5 

Dry 

44 

- 

.  - 

10.27 

— 

256.5 

" 

44 

_ 

10.27 

10.28 

88 

264 

it 

(( 

_ 

_ 

10.29 

- 

269 

n 

I  open 

- 

- 

10.30 

_ 

270 

" 

i« 

_ 

_ 

10.31 

_ 

262 

" 

« 

_ 

10.32 

_ 

241 

a 

44 

_ 

_ 

10.33 

_ 

221 

" 

" 

10.33 

_ 

10.34 

_ 

214.5 

Wet 

44 

_ 

_ 

10.35 

_ 

225 

«* 

Wide  open 

_ 

_ 

10.36 

- 

242 

Dry 

" 

- 

- 

10.38 

87 

261 

" 

" 

_ 

_ 

10.39 

257.5 

44 

I  open 

_ 

- 

10.40 

_ 

255.5 

a 

4  t 

_ 

_ 

10.41 

_ 

259 

a 

44 

_ 

10.41 

10.42 

_ 

265 

it 

" 

_ 

_ 

10.43 

_ 

269.5 

it 

" 

- 

- 

10.44 

_ 

272 

tt 

44 

_ 

_ 

10.45 

_ 

274 

« 

" 

_ 

_ 

10.40 

- 

273 

" 

Wide  open 

- 

- 

10.47 

_ 

253 

ii 

" 

— 

— 

10.48 

- 

227 

44 

I  open 

- 

- 

10.49 

— 

223.5 

M 

" 

— 

— 

10.50 

_ 

235 

" 

" 

_ 

- 

10.51 

_ 

241.5 

« 

" 

10.51 

- 

10.52 

_ 

236 

44 

44 

_ 

- 

10.53 

- 

237 

44 

Wide  open 

- 

- 

10.54 

87 

245 

It 

" 

— 

— 

10.55 

- 

251.5 

" 

\  open 

- 

10.552 

10.56 

_ 

258 

44 

(4 

— 

— 

10.57 

- 

263 

44 

Wide  open 

- 

- 

10.58 

_ 

267.5 

44 

a 

— 

— 

1059 

_ 

265 

" 

44 

_ 

— 

11.00 

- 

235 

Wet 

44 

11.00 

— 

Normal. 

85 

288  (  Rear  pipe.  ) 

1- 

- 

APPENDIX.  265 

In  Table  No.  Itt,  the  indications  of  the  thermometer,  as  also 
data  regarding  the  condition  of  the  issuing  steam  as  it  appeared 
to  the  eye,  the  position  of  the  damper,  and  the  time  of  firing 
of  each  boiler,  are  given  for  nearly  every  minute  during  an 
hour's  test.  The  fluctuating  character  of  the  readings,  as 
influenced  by  the  time  of  firing,  is  clearly  shown  in  this 
record.  Notice,  for  example,  the  reading  at  10.27,  when  the 
boiler  to  which  the  calorimeter  was  applied  was  fired  with 
fresh  coal.  The  reading  is  25G.50,  and,  compared  with  the 
previous  readings,  the  indication  of  the  thermometer  is  rapidly 
rising.  At  10.28  it  reaches  264°,  and  at  10.30  it  is  270°.  At 
this  time  —  three  minutes  after  firing  —  it  is  evident  that  the 
boiler  began  to  recover  its  normal  rate  of  production,  and  the 
indications  of  the  thermometer  began  to  fall.  At  10.33  they 
had  dropped  to  221°,  and  at  the  same  time  the  auxiliary  boiler 
was  fired,  which  occurrence  threw  nearly  the  whole  work  of 
production  upon  the  calorimeter-boiler.  This  was  followed  by 
the  thermometer  going  down  to  214.5°,  and  the  issuing  steam 
assuming  a  wet  appearance  to  the  eye.  The  thermometer 
then  began  to  rise,  and  at  10.38,  five  minutes  afterward,  it 
had  reached  261°.  It  is  presumed  that  the  fire  in  the  auxil- 
iary boiler  had  now  become  quite  active,  while  that  in  the 
calorimeter-boiler  was  somewhat  cooled. 

The  normal  reading  of  the  instrument  was  not  determined 
when  applied  to  the  front  pipe,  but,  taking  the  indication  for 
the  normal  as  determined  for  the  rear  pipe,  which  was  288°, 
the  cooling  effect  due  to  moisture,  for  the  best  indication  — 
viz.,  274°  at  10.45,  is  288°  — 274°=  14°;  and  this,  divided 
by  the  proper  coefficient,  viz.,  21.,  gives  for  the  percentage  of 
moisture,  under  these  circumstances,  0.06.  The  lowest  indica- 
tion, viz.,  214.5°  at  10.34,  shows  a  cooling  effect  due  to 
moisture  of  288° — 214.5°  =  73.5°;  and  this,  divided  by  the 
assumed  coefficient  for  this  temperature,  which  is  1(3.9,  gives, 
for  the  percentage  of  moisture,  4.34  per  cent.  This  percent- 
age, however,  does  not  show  the  whole  of  the  moisture, 
because  the  range  of  the  instrument  was  evidently  exceeded. 

The  record  of  the  test  when  the  calorimeter  was  applied  to 


266 


BOILER    TESTS. 


the  rear  pipe  is  given  in  Table  No.  2n.  The  indications  of 
the  thermometer  vary  from  288°  to  297.5°,  with  a  normal 
reading  of  288°  at  85  pounds  pressure.  There  is  continual 
evidence  here  of  superheating,  and  this  might  be  expected 
from  the  fact  of  the  steam-heating  surface,  of  which  the  steam 
issuing  from  this  end  of  the  drum  had  the  benelit. 

TABLE  No.   2n. 

Double-Deck  Horizontal  Return  Tubular  Boiler  (same  as  preceding}  :  Calori- 
meter Attached  to  Rear  Steam- Pipe. 


Time. 

Boiler  Gauge. 

Temperature  shown  by  lower 
The     ometer  of  Calorimeter 

1.00 

84 

291.5 

1.01 

82.5 

290.5 

1.07 

72 

288 

1.11 

73 

287.5 

1.19 

69 

289.5 

1.23 

71 

289 

1.49 

82 

289.5 

1.54 

88 

292 

1.58 

87.5 

294.5 

2.02 

84 

295.5 

2.04 

82 

295 

2.09 

81 

295.5 

2.12 

84 

296.5 

2.15 

86 

297.5 

2.17 

86.5 

297.5 

2.23 

85 

296 

2.27 

87 

297.5 

Normal 


288 


TEST    O. 

Test  0  was  made  on  a  water  tube  boiler.  On  this  test  the 
heat-gauge  only  was  in  use.  Appended  is  a  table  showing 
the  general  dimensions  of  the  boiler,  and  the  conditions  under 
which  it  was  operated. 


Dimensions  and  other  Data  regarding  Boiler  referred  to  in  Test  0. 


Number  of  sections.        ....... 

Number  of  tubes,  4  in.  outside  diameter,  in  each  section. 

Total  number  of  tubes. 

Diameter  of  drum.         .        .  ' 

Size  of  grate.  .        .        .        .        .        ... 

Area  of  heating  surface 


7.  Area  of  grate  surface.  . 


14 
9 

126 

36  in. 

7x8.5  ft. 

2,765  sq.  ft. 

59.5  " 


APPENDIX.  267 

8.  Ratio  of  heating  surface  to  grate  surface 46.5  to  1 

9.  Kind  of  coal  used.  ....        George's  Creek, Cumberland 

10.  Percentage  of  ashes.      .        .        •  '    .  .        .        .        .  -          6.3  per  ct. 

11.  Coal  consumed  per  hour  per  square  foot  of  grate.       .        .17.9  Ibs. 

12.  Water  evaporated  per  square  foot  of  heating  surface  from 

100  degs.  at  70  Ibs.  pressure  per  hour.        .        .       ' .  .     3.38  Ibs. 

13.  Average  temperature  of  flue  gases.        .        .        .        .  .545  degs. 

14.  Average  draught  suction.        .        .        .        .     '  .        .  .     0.49.  in. 

15.  "Water  per  pound  of  combustible  from  and  at  212  diigs.  .    10.42  Ibs. 

On  this  test,  readings  of  the  instrument  were  taken  at  inter- 
vals of  from  one  to  five  minutes  during  most  of  a  ten  hours' 
run,  and  the  full  set  of  observations  is  given  in  Table  No.  30. 
Eemarks  are  given,  in  connection  with  many  of  the  readings, 
as  to  the  condition  of  the  fire,  height  of  water  in  the  gauge- 
glass,  and  other  information.  It  will  be  seen  from  this  table 
that  the  quantity  of  moisture  in  the  steam  was  quite  variable, 
though  never  excessive.  The  smallest  indication  of  the  lower 
thermometer  was  that  taken  at  4.56  P.M.,  when  the  reading 
was  249°,  and  the  highest  indication  was  at  7.02  A.M.,  when 
the  reading  was  276°.  The  range  corresponds  to  a  little  over 
1  per  cent,  of  moisture.  Using  the  normal  of  280°  for  a 
temperature  of  331°  by  the  upper  thermometer,  which  was 
found  at  a  time  when  the  boiler  was  discharging  little,  if  any, 
steam,  the  lowest  reading  of  249°,  gives  a  cooling  effect  due 
to  moisture  of  280°  —  249°  =  31°,  and  the  highest  reading 
gives  280°  —  276U  =  1°  for  the  cooling  effect  of  moisture. 
The  coefficient  for  330°  is  21°  — that  is,  the  cooling  due  to 
1  per  cent,  of  moisture.  The  two  extreme  percentages  of 

31  1 

moisture  are,  therefore,  —  =  1.48  per  cent.,  and  —  =  0.048 

L\  ,21 

per  cent. 

The  variations  in  the  indications  of  the  lower  thermometer 
were  so  marked,  and  occasionally  so  rapid,  that  an  attempt 
was  made  to  ascertain  whether  these  variations  could  be 
accounted  for  by  any  differences  in  the  condition  of  the  fire, 
the  height  of  water,  or  the  manner  of  feeding  the  water.  At 
one  time  it  was  thought  that  the  lowering  of  the  thermometer 
was  caused  by  an  increased  activity  of  the  fire.  Notice  the 
reading  at  8.42J  A.M.,  which  was  274°,  and  the  next  reading, 


268 


BOILEE  TESTS 


which  fell  to  251°,  1\  minutes  afterward,  and  between  these 
two  readings  the  fire  was  shoved  back,  and  new  coal  added. 
The  next  time,  however,  that  the  fire  was  shoved  back,  which 
was  at  9.12  A.M.,  there  was  no  immediate  change  in  the 
indication  of  the  thermometer,  though  at  9.20  the  reading  had 
fallen  to  259°,  and  this  fall  may  finally  have  been  due  to  the 
increased  activity  of  the  fire.  A  little  farther  on,  at  9.55,  the 
reading  was  2  77°.  Shortly  afterward  the  fire  was  shoved 
back,  and  immediately  the  temperature  fell  to  257°,  and  two 
minutes  later  to  253°.  Take  the  reading,  however,  at  12.28, 
when  the  fire  was  treated  in  the  same  manner  —  there  was  no 
fall  in  the  temperature,  even  after  slicing  the  fire,. and  even 
when  the  water  was  pumped  up  to  quite  a  high  point. 

TABLE    NO.     3  o. 

Water  Tube  Boiler. 


LOWER  THER- 

' 

MOMETER. 

Time. 

Upper 
Thermometer. 

Normal  279 
with  Upper 

Remarks  as  to  Height  of  Water,  State 
of  Fire  and  other  Observations. 

Thermometer 

330.    Say  280  at 

331. 

6.33 

329 

277 

7.02 

331 

279 

7.35 

331 

271 

8.12 

331 

255 

8.20 

331 

272 

8.22i 

331 

276 

8.30 

331 

273 

8-32i 

331 

276 

8.40 

331 

274 

8.42i 

331 

274 

Shove  back  and  fire  at  8.4(5. 

8.50 

330 

251 

8.52i 

330 

252 

8.55 

331 

264 

9.00 

329 

275 

9.05 

330 

271 

9  10 

330 

277 

9.13 

330 

277 

Shove  back  at  9.12. 

9.14 

331 

275 

Firing;  water,  3  inches. 

9.15 

331 

276 

9.20 

331 

259 

9.22i 

331 

251 

Water  41. 

9.25 

331 

265 

9.31 

331 

275 

Shove  back  and  fire,  9.32-33. 

APPENDIX. 
TABLE  NO.  3  o.    (Continued.} 


269 


LOWEK  THER- 

MOMETER. 

Time. 

Upper 
Thermometer. 

Normal  279 
with  Upper 

Kemarks  as  to  Height  of  Water,  State 
of  Fire,  and  other  Observations. 

Thermometer 

330.    Say  280  at 

331. 

9  345 

330 

275 

Water,  55. 

9.35 

330 

271 

9.37 

331 

268 

9.40 

331 

275 

9.45 

331 

276 

9.50 

331 

276 

Front  fired;  water  4  inches. 

9.55 

331 

277 

Water,  3  inches. 

10.015 

331 

257 

Shove  back  and  fire,  9.58-10.00. 

10.035 

331 

253 

Water,  4  inches  ;  feeding  fast. 

10.09 

331 

264 

10.12 

331 

275 

10.17 

330 

277 

10.22 

331 

271 

Front  shoved  back  and  fired. 

10.28 

330 

273 

Water,  55. 

10.32 

331 

252 

M      41. 

10.35 

331 

271 

10.41 

330 

275 

10.45 

330 

260 

Water,  65. 

10.50 

331 

256 

Front  shoved  back  and  fired. 

10.55 

331 

250 

Water,"  6  ;  pump  slow. 

11.07 

330 

263 

Feeding  fast  ;  height,  4  inches. 

11.15 

331 

260 

11.151 

331 

251 

Height,  5t 

11.18 

330 

256 

Front  fired,  height,  6. 

11.201 

— 

263 

11.22 

331 

258 

11.23 

331 

253 

11.32 

331 

259 

11.35 

331 

274 

Front  fired  ;  height,  6. 

11.38 

330 

276 

11.41 

330 

275 

11.43 

331 

256 

Water,  11. 

11.45 

331 

261 

Front  shoved  back. 

11.47 

331 

267 

11.50 

331 

260 

Height,  65. 

11.55 

331 

262 

6  . 

12.00 

331 

253 

7. 

12.06 

332 

277 

He  ght,  7  ;  damper  shut. 

12.10 

332 

259 

'        7;         "       open. 

12.15 

332 

260 

65. 

12.22 

332 

252 

5. 

12.28 

331 

275 

Front  shoved  back  and  firing. 

12.31 

330 

277 

Height,  5. 

12  34 

329 

275 

12.38 

328 

275 

Front  sliced;  height,  7. 

12.40 

327 

271 

12  45 

327 

273 

12.51 

329 

275 

270 


BOILER    TESTS. 
TABLE  NO.  3  o.    (Concluded.} 


LOWER  THER- 

MOMETER. 

Time. 

Upper 
Thermometer. 

Normal  279 

Kemarks  as  to  Height  of  Water,  State 
of  Fire,  and  other  Observations. 

with  Upper 

Thermometer 

330.    Say  280 

at  331. 

12.59 

330 

258 

Height,  7. 

1.13 

330 

275 

"        7. 

1.21 

330 

276 

8. 

1.30 

330 

277 

4. 

1.38 

330 

261 

Feeding  fast;  height  5. 

1.43 

329 

262 

Front  shoved  back  and  fired. 

1.50 

330 

264 

Feeding  fast  ;  height  6. 

1.57 

330 

256 

Height,  5.5. 

2.08 

331 

266 

5.5. 

2.14 

331 

253 

5.2. 

2.20 

330 

273 

Shoved  back,  2.21. 

2.22 

329 

268 

Fired,  2.22L 

2.23 

329 

261 

2.24 

329 

259 

2.25 

329 

252 

2.26J 

329 

252 

Height,  6.5. 

2.28 

329 

255 

Slow  down  pump,  2.29£. 

2.30 

330 

269 

2.35 

331 

276 

2.46 

331 

261 

Height,  3. 

2.52 

331 

263 

Shove  back,  2.50. 

2.54 

330 

256 

3.04 

331 

266 

Height,  3. 

3.09 

330 

276 

3. 

3.20 

331 

255 

2.5. 

3.25 

331 

255 

3. 

3.32 

331 

273 

4. 

3.40 

331 

275 

Shoved  back  and  fired,   3.35; 

height,  6.5. 

3.45 

331 

277 

Height.  5. 

3.53 

331 

268 

Height,  3.5. 

3.59 

331 

270 

4.5. 

4.06 

331 

264 

3.5. 

4.11 

331 

271 

Shoved  back,  4.10;  fired,  4.11L 

4.12 

331 

270 

Height,  3.5.  (?) 

4.13 

331 

271 

4.14 

331 

266 

Height,  5.5. 

4.15 

331 

262 

6. 

4.17 

330 

273 

4.24 

331 

265 

Height,  4.5. 

4.28 

330 

273 

4. 

4.39 

326 

275 

4. 

4.45 

326 

275 

4.5. 

4.53 

330 

258 

Front  shoved  back   and  fired, 

height,  5.5. 

4.56 

330 

249 

Height,  6.5. 

5.04 

330 

276 

5.5. 

5  16 

331 

276 

5.22 

331 

275 

Height,  5.5. 

5.28 

333 

276 

Damper  shut. 

5  33 

331 

278 

Height,  5.4. 

APPENDIX. 


271 


TEST   P. 

Test  P  was  made  on  a  plant  of  two  horizontal  return  tubular 
boilers,  and  in  this  case  the  complete  form  of  the  instrument 
was  used.  The  full  set  of  observations  is  given  in  Table  No. 
4tp.  Considerable  interest  attaches  to  this  test  on  account  of 
the  priming  of  one  of  the  boilers,  which  was  brought  about  by 
design.  This  boiler  was  filled  with  water  to  nearly  the  top 
of  the  glass,  and  the  bituminous  coal  fire  was  barred  up,  the 
damper  opened  wide,  and  the  boiler  made  to  do  its  maximum 
amount  of  work.  The  time  when  this  occured  was  2.05  P.M., 
and  shortly  afterward  the  quantity  of  water  collecting  in  the 
drip-box  began  to  increase,  and  for  the  seven  and  a  half 
minutes  between  2.15  and  2.22|,  18.9  ounces  of  water  were 
withdrawn.  This  represents  9.28  pounds  per  hour,  or  about 
18.5  per  cent,  of  moisture,  the  quantity  of  steam  used  being 
estimated  at  50  pounds  per  hour. 

Taking  the  ordinary  indications  of  the  instrument  during 
the  20  minutes'  time  between  12.55  and  1.15  P.M.,  the  drip- 
box  discharged  2.7  ounces,  or  0.51  of  a  pound  per  hour.  The 
average  reading  of  the  upper  thermometer  was  304.9°  ;  and  of 
the  lower  thermometer,  268.2°.  Comparing  these  observa- 
tions with  the  normal  readings,  it  is  seen  that  there  was  but  a 
trifling  indication  of  moisture. 

It  may  be  added  that  the  priming  was  found  to  be  due,  when 
the  water  was  carried  too  high,  to  the  presence  of  vegetable 
matter  in  the  water,  and  to  too  infrequent  blowing  off. 

TABLE  No.  4p. 

Two  Horizontal  Return  Tubular  Boilers,  Complete  Calorimeter  in  Use. 


Time. 

Upper  Ther- 
mometer. 

Lower  Ther- 
mometer. 

Height  of 
Water  in  Glass 
in  Sixteenths 

Remarks. 

of  an  inch. 

12.22J 

306 

265 

3 

Practically  no 

12.25 

304.5 

267 

5 

steam  drawn  off 

12.271 

302 

267 

7  scant 

from  boilers 

12.30 

301 

267 

8  sea  t 

between  12.  25^  and 

12.32J 

303 

267 

10 

12.47J 

12.35 

305 

267 

13  + 

12.37i 

303 

268 

15  + 

12.40 

304 

268.5 

17  scant 

12.42& 

304 

268.5 

18  + 

Draw  off  from 

12.45 

303 

268 

20 

drip-box,  at  12.46, 

12  479 

302 

267 

2  + 

2.7  ounces. 

272 


BOILER   TESTS. 


TABLE  No.   4 p.     (Continued.} 


Time. 

Upper   Ther 
mometer. 

Lower  Ther- 
mometer. 

Height  of  Water 
in  Glass  in 
Sixteenths  of 
an  inch 

Remarks. 

Average    \ 
normal     [• 
readings.  J 

303.6 

267.3 

1"    .39  Ib.  per 
hour 

12.50 

302 

267 

4  + 

12.52J 

302 

267 

6  scant 

12.55 

303 

267 

8  + 

Engine  started 

12.575 

303 

267 

11 

at  12.55. 

1.00 

303 

267 

14 

1.02J 

305 

268 

16  + 

1.05 

306 

268 

19 

1.071 

307 

269 

21  + 

1.10 

307 

269 

24 

1.12-J 

30G 

270 

7 

Draw  off   from 

1.15 

304 

269 

8  + 

drip-box,  at  1.11, 

1.171 

302 

268 

9  + 

2.7  ounces. 

1.20 

301 

268 

10-*- 

1.22-5 

302 

267 

12  + 

1.25 

302 

267 

14  + 

1.271 

302 

267 

16  + 

1.30 

304 

267 

19 

1.32J 

304 

268 

22 

1.35 

304 

268 

23 

Draw  off  from 

1.37J 

303 

268 

5.5 

drip-box,  at 

1.40 

301 

268 

6  + 

1.36,  2.7  ounces. 

1.42J 

300 

267 

8 

1.45 

298 

266 

10 

Water  being 

1.471 

298 

266 

10  + 

pumped  to  a  high 

1.50 

300 

265 

13 

point. 

1.52J 

302 

265 

16 

Draw  off  from 

1.55 

304 

266 

19 

drip-box,  at  2.  01, 

1.575 

306 

267 

22 

2.7  ounces. 

2.00 

306.5 

268 

24 

At  2.05   damper 

2.02J 

307 

269 

8 

of    one    boiler 

2.05 

307 

270 

11 

shut.     Fire  in 

2.075 

308 

270 

22  + 

the  other  boiler 

2.10 

306 

270 

29 

barred  up  and 

2.121 

308 

270 

12 

water  at  a  high 

2.15 

307 

270 

14 

point. 

2.225 

306 

255 

12 

Draw  off  from 

2.25 

308 

266 

15 

the  drip-box,  at 

2.27£ 

310 

270 

18  + 

2.11,  2.7  ounces. 

2.30 

310 

270 

20  + 

Between  2.15  and 

2.325 

310 

270 

21  + 

2.22    draw    off 

from   drip-box 

• 

18.9  ounces. 

APPENDIX. 
TABLE  No.  4 p.     (Concluded.) 


273 


Height  of  Water 

Time. 

Upper  Ther- 
mometer. 

Lower  Ther- 
mometer. 

in  Glass  in 
Sixteenths  of 
an  inch. 

Remarks. 

2.35 

309 

271 

23 

At  2.25  height  of 

2.37J 

310 

271 

7 

water    in    the 

2.42^ 

301 

268 

8 

active      boiler 

2.45 

298 

267 

8  + 

had     fallen    4 

2.475 

299 

266 

10 

inches. 

2.50 

301 

266 

12 

Draw  off  from 

2.521 

305 

267 

17 

drip-box,  at  2.36, 

2.55 

308 

266 

21 

2.7  ounces.     At 

2.571 

310 

269 

23 

2.421  dampers  of 

3.00 

312 

270 

24  + 

both  boilers  open. 

INDEX. 


Air  above  fuel,  Boilers  which  admit,  81,  89,  111,  123,  132,  157,  192,  217,  224. 

Air  above  fuel,  Prevention  of  smoke  by  admitting,  54,  02,  113,  137. 

Air  and  steam  through  cast  iron  globes  at  bridge  wall,  Economy  of  admit- 
ting, 89,  179. 

Air  at  bridge  wall,  Economy  of  admitting,  52,  111. 

Air  leakage  through  unsound  brick  work,  201,  215,  232. 

Air  over  fuel,  Economy  of  admitting,  52,  53,  54,  55,  50,  83,  91,  111,  125, 
133,  195. 

Air  space  in  grates,  Tests  with  different  proportions  of,  00,  95. 

Air  through  bridge  wall  and  through  side  walls  of  furnace,  Economy  of 
admitting,  55,  83,  125,  133,  195. 

Air  through  bridge  wall  and  through  supplementary  wall  behind  it, 
Economy  of  admitting,  54,  158. 

Allowance  for  superheating,  22,  180. 

Alternate  firing,  Boiler  with  two  furnaces  for,  38,  121. 

Anthracite  coal,  Tests  with,  67,  73,  78,  89,  92,  90,  98,  102,  104,  107,  113,  110, 
119,  120,  127,  129,  131,  140,  149,  154,  102,  105,  109,  174,  177,  179,  183, 
187,  190,  192,  196,  199,  201,  211,  213,  217,  219,  221,  222,  228. 

Artificial  draught  with  blower,  Economy  of,  01,  87. 

Ash  in  different  coals,  Percentage  of,  111,  104. 

Automatic  vs.  hand  regulation  of  draught,  00,  94. 

Banking  fires,  Loss  from,  62,  179. 

Barrel  Calorimeter,  17. 

Bituminous  coal,  Tests  with,  70,  78,  89,  101,  110,  121,  132,   134,   130,  139, 

140,  145,  148,  150,  152,  150,  157,  159,  103,  166,  168,  171,  179,  180,  194, 

203,  205,  208,  215,  224,  230,  231. 
Blower  draught,  Boilers  with,  70,  75,  80,  190. 
Boiler  setting,  51. 

Boilers,  Cast  iron  Sectional,  211,  213,  215. 
Boilers,  Direct  Tubular,  80,  105,  149. 
Boilers,  double-deck,  159  to  171. 
Boilers,  Galloway,  180. 

Boilers,  Horizontal  Return  Tubular,  07  to  157. 
Boilers,  Plain  Cylinder,  174  to  180. 
Boilers,  Plant  of  two  or  mor3,  See  Plant. 

(274) 


IXDEX.  275 

Boilers,  Vertical  Tubular,  183  to  210. 

Boilers,  Water  Tube,  217  to  233. 

Boilers    with  miscellaneous   details   of   construction,    See  Air,   Alternate 

firing,   Blower,    Detached   furnace,   Double  passage,    Eire    box,  Flue 

heater,  Superheating,  Water  leg. 
Brick  arch  in  furnaca,  Boiler  with,  149. 
Bridge  wall,  Effect  of  shape  of,  upon  economy,  51. 
Broken  coal,  Tests  with  Anthracite,  73,  78,  101,  107,  118,  121,  131,  148,  150, 

163,  16G,  169,  183,  194,  197. 

Calorimeter,  Barrel,  17. 

Calorimeter  for  determining  heat  of  combustion  of  coal,  Appendix. 

Calorimeter,  Superheating,  18,  19. 

Calorimeter  tests  of  the  quality  of  steam,  62. 

Calorimeter,  Universal  steam,  Appendix. 

Cast  Iron  Sectional  Boilers,  211,  213,  215. 

Cast  Iron  Sectional  Boilers,  Comparative  economy  of,  40. 

Cast  Iron  Sectional  Boiltrs   with  flue  heater,  213. 

Chestnut  coal,  Tests  with,  67,  102,  104,  107,  217. 

Chestnut  No.  2  coal,  Economy  of,  49. 

Chestnut  No.  2  coal,    115,  127,  174,  179,  199,  213. 

Coal,  Cambria  bituminous,  215,  230. 

Coal,  Clearfleld  bituminous,  203. 

Coal,  Cumberland,  70,  79,  91,  101,  110,  121,  122,  136,  139,148,   150,  157,  159, 

163,  166,  168,  171,  179,  180,  194,  205,  208,  224. 
Coal,  Delaware  and  Lackawanna  Broken,  169. 
Coal,  Franklin,  81. 
Coal,  Hazelton  Chestnut,  67. 

Coal,  Honeybrook  Lehigh  Chestnut,  pea  and  broken,  107. 
Coal,  Kalmia,  81. 

Coal,  Lackawanna  Broken,  73,  79,  101,  163,  166,  183, 
Coal,  Lackawanna  Chestnut  No  2.,  228. 
Coal,  Lehigh  Broken,  101,  121,  194,  197,  221. 
Coal,  Lehigh  Chestnut,  102,  104,  107,  217. 
Coal,  Lehigh  Chestnut  No.  2,  222. 
Coal,  Lehigh  Egg,  91,  126,  187. 
Coal,  Mixture  of  Buckwheat  and  Clearfleld,  142. 
Coal,  Mixture  of  Pea  and  Dust  and  Clearfield,  115. 
Coal,  Mixture  of  Pea  and  Dust  and  Cumberland,  79,  86,  110,  123. 
Coal,  Mixture  of  Pea  and  Dust  and  Nova  Scotia  Culm,  79,  118,  166. 
Coal,  Mixture  of  Pea  and  Dust  and  Powelton,  227. 
Coal,  Mixture  of  Screenings  and  Cumberland,  91,  101,  150,  194,  197. 
Coal,  Mixture  of  Screenings  and  Nova  Scotia  Culm,  75,  81. 
Coal,  Nova  Scotia  Culm,  132,  134,  166. 
Coal,  Ohio  Lump,  50,  152. 

Coal,  Philadelphia  and  Reading  Broken,  148,  150. 
Coal,  Schuylkill  Broken,  191. 
Coal  screenings,  191. 


276  INDEX. 

Coal,  Shamokin  Pea,  219. 

Coal,  Walston  bituminous,  49,  145,  156. 

Coal,  White  Ash  Broken,  118,  131. 

Coal,  Wilkesbarre,  154. 

Coke,  Boilers  using,  and  economy  of  same,  50,  139,  178. 

Combustion  chamber  or  space  behind  bridge  wall,  Arrangement  of,  61. 

Commercial  tests,  Engineering  tests  and,  11,  12. 

Comparison   between  boiler  with  air  admission,   and  boiler  without  air 

admission,  above  fuel,  52,  123,  132. 
Comparison  between  boiler  with  three  inch  tubes,  and  boiler  with  thrae  and 

a  half  inch  tubes,  35,  134. 

Comparison  between  different  kinds  of  boilers,  36. 
Comparison  between  double-deck  boilers  and  ordinary  horizontal  tubular 

boilers,  39,  162. 
Comparison  between  economy  of  different  kinds  of  fuel,  43,  109,  113,  116, 

149,  162,  196. 
Comparison  between  saturated  steam  boilers  and  superheated  steam  boilers, 

22. 

Comparison  between  vertical  boilers  and  horizontal  tubular  boilers,  23,  186. 
Comparative  draught  required  for  different  fuels,  48,  49,  119. 
Comparative  labor  of  firing  different  fuels,  80,  119. 
Computing  results,  Method  of,  19,  20,  21. 
Conducting  ideal  tests,  Method  of,  12. 
Conducting  tests  given  in  Part  II,  Method  of,  13,  14,  15. 

Detached  furnace,  Boilers  with,  36,  86,  149. 

Direct  tubular  boiler  with  common  furnace,  104. 

Direct  tubular  boilers  with  detached  furnace,  86,  149. 

Direct  tubular  boilers  with  detached  furnace,  Comparative  economy  of,  37. 

Double-dyck  boilers,  159  to  171. 

Double-deck  boilers,  Comparative  economy  of,  39  163. 

Double  furnace  for  alternate  firing,  Hor.  Ret.  Tub.  boiler  with,  38,  121. 

Double  passage  for  products  of  combustion,  Boilers  with,  75.  98,  154. 

Draught  with  blower,  Economy  of  artificial,  61,  88. 

Draught,  Automatic  vs.  hand  regulation  of,  60,  94. 

Draught,  Effect  of  flue  heater  on,  58. 

Draught  for  vertical  boilers,  195,  202. 

Draught  gauge,  16. 

Draught,  Method  of  taking,  16. 

Economical  temperature  of  escaping  gases  with  anthracite  and  bituminous 

coal,  28,  31. 

Economy  of  carrying  high  water  in  vertical  boiler,  187. 
Economy  of  flue  heaters,  56,  145,  174,  207,  226. 
Economy  of  wetting  bituminous  coal,  61. 

Effect  of  admitting  air  above  fuel  in  preventing  smoke,  53,  62,  113,  137,  159. 
Effect  of  admitting  air  above  fuel  upon  flue  temperature,  113. 
Effect  of  admission  of  air  through  unsound  brick  work  upon  draught  and 

economy,  26,  201,  215,  232. 


INDEX.  277 

Effect  of  flue  heater  on  draught,  58. 
Effect  of  flue  temperature  on  economy,  26,  28. 

Effect  of  proportion  of  tube  area  to  grate  surface  upon  economy,  34. 
Effect  of  size  of  shell  upon  economy,  34. 
Effect  of  size  of  tubes  upon  economy,  35. 
Engineering  tests  and  commercial  tests,  11,  12. 

Escaping  gases,  Economical  temperature  of,  with  Anthracite  and  bitumin- 
ous coal,  28. 

Feed  water  heated  by  coil  of  pipe  in  flue,  76,  221. 

Feed  water,  Method  of  weighing,  15. 

Fire  box  vertical  boilers,  27,  187,  203,  208. 

Flue  heater,  Boilers  with,  142,  171,  205,  213,  224. 

Flue  heaters,  Economy  of,  56,  145,  174,  207,  226. 

Flue  heater  with  cast-iron  sectional  boilers,  213. 

Flue  heater  with  horizontal  tubular  boilers,  142,  171. 

Flue  heater  with  vertical  tubular  boilers,  205. 

Flue  heater  with  water  tube  boilers,  224. 

Flue  temperature,  Effect  of,  upon  economy,  28. 

Forced  draught,  Boilers  provided  with,  70,  75,  86,  190. 

Free  burning  coal,  145,  152. 

Furnace  for  burning  bituminous  coal  without  smoke,  136. 

Galloway  boiler,  180. 

Galloway  boiler,  Comparative  economy  of,  42. 

Gases,  Economical  temperature  of,  with  Anthracite  and  bituminous  coal,  28. 
General  conditions  under  which  tests  were  made,  12,  13. 
General  conditions  which  secure  economy,  28. 

Grates  with  50  per  cent,  air  space,  vs.  grates  with  60  per  cent,  air  space, 
Economy  of,  95. 

Hand  regulation  vs.  automatic  regulation  of  draught,  60,  94. 

Heated  air  above  fuel,  Boiler  supplied  with,  84. 

Heating  feed  water  by  coil  of  pipe  in  flue,  76,  221. 

High  flue  temperature  in  cast-iron  sectional  boilers,  plain  cylinder  boilers, 

and  Galloway  boiler,  31. 
High  flue  temperature  in  vertical  boilers,  26. 
High  water  in  vertical  boiler,  Economy  of,  187. 
Horizontal  direct  tubular  boiler  with  common  furnace,  105. 
Horizontal  direct  tubular  boiler  with  detached  furnace,  86,  149. 
Horizontal  return  tubular  boiler,  42  inch,  154,  156. 

Horizontal  return  tubular  boiler,  48  inch,  67,  78,  92,  96,  102,  104,  129,  130. 
Horizontal  return  tubular  boiler,  54  inch,  81,  145. 
Horizontal  return  tubular  boiler,  60  inch,  113,  123,  131,  157. 
Horizontal  rsturn  tubular  boiler,  66  inch,  138. 
Horizontal  return  tubular  boiler,  72  inch,  127,  134,  152. 
Horizontal  return  tubular  boiler  with  additional  pipe  surface  in  furnace,  67, 

142. 


278  INDEX. 

Horizontal  return  tubular  boiler  with  double  passage  for  products  or  com- 
bustion, 38,  75,  98,  134. 

Horizontal  return  tubular  boiler  with  superheater,  67,  154. 
Horizontal  return  tubular  boiler  with  water  leg  front,  89,  107. 

Influence  of  flue  heater  on  the  draught,  59. 
Interests  which  led  to  tests,  9. 

Labor  of  firing  with  different  fuels,  Comparative,  80,  119,  196. 

Leakage  of  air  through  unsound  brick  work,  26,  201,  215,  232. 

Location  of  boilers  tested,  10. 

Loss  by  air  leakage  through  unsound  brick  work,  26,  201,  215,  232. 

Loss  by  banking  flre,  62,  179. 

Loss  of  heat  in  vertical  boilers  at  chimney,  26. 

Meaning  of  lines  given  in  tables,  19. 
Method  of  computing  results,  20. 
Method  of  conducting  ideal  tests,  12. 
Method  of  conducting  tests  given  in  Part  II,  13. 
Method  of  determining  quality  of  steam,  17. 
Method  of  taking  temperature  and  draught  suction,  16. 
Method  of  weighing  feed  water,  15. 

Mixture  of  Anthracite  and  bituminous  coal,  Tests  with,  75,  79,  81,  84,  91, 
101,  109,  115,  118,  123,  142,  150,  166,  194,  197. 

Object  of  boiler  tests  in  general,  11. 

Pea  coal,  Tests  with  Anthracite,  110,  118,  178,  219. 

Petroleum  oil  from  Canada,  Test  with,  151. 

Petroleum,  Tests  with,  50,  97,  150. 

Pipes  beneath  boiler  shell  in  furnace,  Effect  of,  upon  economy,  67,  142. 

Plain  cylinder  boilers,  39,  174,  177,  179. 

Plant  of  two  cast-iron  sectional  boilers,  215. 

Plant  of  ten  cast-iron  sectional  boilers  with  flue  heater,  213. 

Plant  of  three  60-inch  double-deck  boilers,  162. 

Plant  of  four  54-inch  double-deck  boilers,  168. 

Plant  of  four  48-inch  double-deck  boilers  with  flue  heater,  171. 

Plant  of  six  Galloway  boilers,  180. 

Plant  of  three  48-inch  horizontal  return  tubular  boilers,  116. 

Plant  of  six  48-inch  horizontal  return  tubular  boilers,  73. 

Plant  of  two  60-inch  horizontal  return  tubular  boilers,  126. 

Plant  of  three  60-inch  horizontal  return  tubular  boilers,  146. 

Plant  of  four  60-inch  horizontal  return  tubular  boilers,  122. 

Plant  of  six  60-inch  horizontal  return  tubular  boilers,  84. 

Plant  of  three  66-inch  horizontal  return  tubular  boilers,  138. 

Plant  of  two  72-inch  horizontal  return  tubular  boilers,  132. 

Plant  of  three  72-inch  horizontal  return  tubular  boilers,  127. 

Plant  of  two  48-inch  horizontal  return  tubular  boilers  and  one  furnace,    70. 


INDEX.  279 

Plant  of  six  60-inch  horizontal  return  tubular  boilers  with  double  passage 
for  products  of  combustion,  75. 

Plant  of  two  54-inch  horizontal  return  tubular  boilers  with  flue  heater,  140, 

Plant  of  two  60-inch  horizontal  return  tubular  boilers  with  flue  heater,  142. 

Plant  of  four  plain  cylinder  boilers,  174. 

Plant  of  five  vertical  tubular  boilers,  196. 

Plant  of  two  vertical  tubular  fire  box  boilers  with  large  heating  sur- 
face, 208. 

Plant  of  two  vertical  tubular  fire-box  boilers,  without  superheating,  203. 

Plant  of  two  vertical  tubular  nest  boilers,  199. 

Plant  of  two  vertical  tubular  rolling-pin  boilers  with  flue  heater,  205. 

Plant  of  two  water-tube  boilers,  231. 

Plant  of  two  water-tube  boilers  with  flue  heater,  224. 

Plant  of  four  water-tube  boilers  with  coil  of  pipe  in  flue,  219. 

Power,  Relative,  with  different  fuels,  48,  80,  91,  102. 

Prevention  of  smoke,  53,  62,  113,  122,  137,  159. 

Prevention  of  smoke  by  admitting  air  above  fuel,  53,  62,  113,  137,  159. 

Proportion  of  heating  surf  ace  to  grate  surf  ace,  Effect  of,  upon  economy,  32. 

Proportion  of  heating  surface  for  best  results,  32. 

Proportion  of  tube  opening  to  grate  surface,  Effect  of,  upon  economy,  34. 

Proportions  of  air  space  in  grates,  Tests  with  different,  60,  95. 

Quality  of  steam,  Method  of  determining,  17. 
Quality  of  steam,  Calorimeter  tssts  of  the,  62. 

Rapid  combustion,  Economy  of,  183,  187,  198. 

Rate  of  combustion,  Effect  of  changing,  103,  106,  108,  168,  176,  189,   198, 

202. 

Relative  amount  of  power  developed  with  different  fuels,  48,  80,  91,  102. 
Relative  economy  of  different  kinds  of  boilers,  36, 
Relative  economy  of  different  kinds  of  fuel,  43,  80,  101,  109,  115,  118,  150, 

163,  166,  194,  197. 
Relative  labor  of  firing  different  coals,  80,  119,  196. 

Screenings  burned  with  forced  draught,  Tests  with,  86,  190. 

Sectional  boilers,  Cast  iron,  211,  213,  215. 

Shape  of  bridge  wall,  Effect  of,  upon  economy,  51. 

Size  of  shell,  Effect  of,  upon  economy,  34. 

Size  of  tubes,  Effect  of,  35,  134. 

Smokeless  furnace,  136. 

Steam  heating  surface  at  top  of  shell,  Effect  of,  67,  93. 

Stove  coal,  Tests  with,  115. 

Summary  of  Tests,  234. 

Summary  of  Tests  with  flue  heaters,  57. 

Superheated  steam,  Boilers  producing,  67,  154,  183,  187,  190,  192,  196,  199, 

201,  205,  209,  211,  215. 

Superheater  with  horizontal  boiler  and  auxiliary  furnace,  67. 
Superheating,  Allowance  for,  22,  186. 


280  ItfDEX. 

Superheating  boilers,  Comparison  between  saturated  steam  boilers  and,  22. 

Superheating  calorimeter,  18. 

Superheating  steam  in  an  independent  superheater,  28,  69. 

Superheating  to  different  degrees  with  cast  iron  sectional  boiler,  211. 

Superheating  with  cast  iron  sectional  boiler,  215. 

Superheating  with  horizontal  tubular  boiler,  154. 

Table  No.  1,  Results  of  tests  of  horizontal  tubular  boilers,  24. 

Table  No.  2,  Results  of  tests  of  vertical  tubular  boilers,  25. 

Table  No.  3,  Results  of  tests  of  horizontal  tubular  boilers  with  high  flue 

temperature,  anthracite  coal,  29. 
Table  No.  4,  Results  of  tests  of  horizontal  tubulars  boilers,  with  low  flue 

temperature,  anthracite  coal,  29. 
Table  No.  5,  Results  of  tests  of  horizontal  tubular  boilers  with  Cumberland 

coal,  30. 

Table  No.  6,  Results  of  tests  of  water  tube  boilers,  41. 
Table  No.  7,  Comparative  results  of  tests  with  different  fuels,  referred  to 

anthracite  coal,  44. 
Table  No.  8,  Comparative  cost  of  coal  and  labor  with  different  fuels,  foi 

1000  H.  P.  plant,  47. 

Table  No.  9,  Summary  of  tests  with  flue  heaters,  57. 
Table  No.  10,  Influence  of  flue  heater  on  the  draught,  59. 
Temperature  and  draught  suction,  Method  of  determining,  16. 
Tube  opening  to  grate   surface,  Effect  of  proportion  of,  upon  economy, 

34. 
Tubes,  Effect  of  size  of,  upon  economy,  35. 

Use  of  additional  heating  surface  applied  to  boiler  in  furnace,  61. 

Value  of  superheated  steam  for  motive  power,  23. 

Vertical  tubular   boilers,  22,  39,  183,  187,    190,    192,    196,    199,   201,    203, 

205,  208. 

Vertical  tubular  boiler  with  interior  chamber,  187,  190. 
Vertical  tubular  boilers  with  flue  heater,  205. 
Vertical  tubular  fire-box  boilers,  27,  187,  203,  208. 
Vertical  tubular  rolling-pin  boilers,  183,  192,  201. 

Water  leg  front,  Boilers  with,  38,  89,  107. 

Water  tube  boilers,  217,  219,  221,  222,  224,  228,  230,  231. 

Water  tube  boilers,  Relative  economy  of,  40. 

Wet  steam  produced  by  discharging  water  into  steam  space,  72. 

Wetting  bituminous  coal,  Economy  of,  62,  167. 


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